diff --git a/docs/generated/sql/bnf/BUILD.bazel b/docs/generated/sql/bnf/BUILD.bazel
index c16ed534f90b..94fee4bd0e86 100644
--- a/docs/generated/sql/bnf/BUILD.bazel
+++ b/docs/generated/sql/bnf/BUILD.bazel
@@ -74,6 +74,7 @@ FILES = [
     "create_database_stmt",
     "create_ddl_stmt",
     "create_extension_stmt",
+    "create_func_stmt",
     "create_index_stmt",
     "create_inverted_index_stmt",
     "create_role_stmt",
@@ -126,6 +127,9 @@ FILES = [
     "insert_stmt",
     "iso_level",
     "joined_table",
+    "legacy_begin_stmt",
+    "legacy_end_stmt",
+    "legacy_transaction_stmt",
     "like_table_option_list",
     "limit_clause",
     "move_cursor_stmt",
@@ -163,6 +167,8 @@ FILES = [
     "resume_stmt",
     "revoke_stmt",
     "rollback_transaction",
+    "routine_body_stmt",
+    "routine_return_stmt",
     "row_source_extension_stmt",
     "savepoint_stmt",
     "scrub_database_stmt",
@@ -226,6 +232,7 @@ FILES = [
     "split_table_at",
     "stmt",
     "stmt_block",
+    "stmt_without_legacy_transaction",
     "table_clause",
     "table_constraint",
     "table_ref",
diff --git a/docs/generated/sql/bnf/begin_stmt.bnf b/docs/generated/sql/bnf/begin_stmt.bnf
index 16c09600aae2..1059df25a0ad 100644
--- a/docs/generated/sql/bnf/begin_stmt.bnf
+++ b/docs/generated/sql/bnf/begin_stmt.bnf
@@ -1,19 +1 @@
 begin_stmt ::=
-	'BEGIN' 'TRANSACTION' 'PRIORITY' 'LOW' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'PRIORITY' 'NORMAL' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'PRIORITY' 'HIGH' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'READ' 'ONLY' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'READ' 'WRITE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'DEFERRABLE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 'NOT' 'DEFERRABLE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN' 'TRANSACTION' 
-	| 'BEGIN'  'PRIORITY' 'LOW' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'PRIORITY' 'NORMAL' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'PRIORITY' 'HIGH' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'READ' 'ONLY' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'READ' 'WRITE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'AS' 'OF' 'SYSTEM' 'TIME' a_expr ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'DEFERRABLE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  'NOT' 'DEFERRABLE' ( ( ( ',' |  ) ( ( 'PRIORITY' ( 'LOW' | 'NORMAL' | 'HIGH' ) ) | ( 'READ' 'ONLY' | 'READ' 'WRITE' ) | ( 'AS' 'OF' 'SYSTEM' 'TIME' a_expr ) | ( 'DEFERRABLE' | 'NOT' 'DEFERRABLE' ) ) ) )*
-	| 'BEGIN'  
diff --git a/docs/generated/sql/bnf/commit_transaction.bnf b/docs/generated/sql/bnf/commit_transaction.bnf
index 852a7e983367..f4d95a9e6f30 100644
--- a/docs/generated/sql/bnf/commit_transaction.bnf
+++ b/docs/generated/sql/bnf/commit_transaction.bnf
@@ -1,5 +1,3 @@
 commit_stmt ::=
 	'COMMIT' 'TRANSACTION'
 	| 'COMMIT' 
-	| 'END' 'TRANSACTION'
-	| 'END' 
diff --git a/docs/generated/sql/bnf/create_ddl_stmt.bnf b/docs/generated/sql/bnf/create_ddl_stmt.bnf
index c14860b51768..308db39242eb 100644
--- a/docs/generated/sql/bnf/create_ddl_stmt.bnf
+++ b/docs/generated/sql/bnf/create_ddl_stmt.bnf
@@ -7,3 +7,4 @@ create_ddl_stmt ::=
 	| create_type_stmt
 	| create_view_stmt
 	| create_sequence_stmt
+	| create_func_stmt
diff --git a/docs/generated/sql/bnf/create_func_stmt.bnf b/docs/generated/sql/bnf/create_func_stmt.bnf
new file mode 100644
index 000000000000..6261dca3715a
--- /dev/null
+++ b/docs/generated/sql/bnf/create_func_stmt.bnf
@@ -0,0 +1,2 @@
+create_func_stmt ::=
+	'CREATE' opt_or_replace 'FUNCTION' func_create_name '(' opt_func_arg_with_default_list ')' 'RETURNS' opt_return_set func_return_type opt_create_func_opt_list opt_routine_body
diff --git a/docs/generated/sql/bnf/legacy_begin_stmt.bnf b/docs/generated/sql/bnf/legacy_begin_stmt.bnf
new file mode 100644
index 000000000000..3974be960389
--- /dev/null
+++ b/docs/generated/sql/bnf/legacy_begin_stmt.bnf
@@ -0,0 +1,2 @@
+legacy_begin_stmt ::=
+	'BEGIN' opt_transaction begin_transaction
diff --git a/docs/generated/sql/bnf/legacy_end_stmt.bnf b/docs/generated/sql/bnf/legacy_end_stmt.bnf
new file mode 100644
index 000000000000..51e539de45ac
--- /dev/null
+++ b/docs/generated/sql/bnf/legacy_end_stmt.bnf
@@ -0,0 +1,2 @@
+legacy_end_stmt ::=
+	'END' opt_transaction
diff --git a/docs/generated/sql/bnf/legacy_transaction_stmt.bnf b/docs/generated/sql/bnf/legacy_transaction_stmt.bnf
new file mode 100644
index 000000000000..86e69e3eaa9c
--- /dev/null
+++ b/docs/generated/sql/bnf/legacy_transaction_stmt.bnf
@@ -0,0 +1,3 @@
+legacy_transaction_stmt ::=
+	legacy_begin_stmt
+	| legacy_end_stmt
diff --git a/docs/generated/sql/bnf/routine_body_stmt.bnf b/docs/generated/sql/bnf/routine_body_stmt.bnf
new file mode 100644
index 000000000000..f6143b545995
--- /dev/null
+++ b/docs/generated/sql/bnf/routine_body_stmt.bnf
@@ -0,0 +1,3 @@
+routine_body_stmt ::=
+	stmt_without_legacy_transaction
+	| routine_return_stmt
diff --git a/docs/generated/sql/bnf/routine_return_stmt.bnf b/docs/generated/sql/bnf/routine_return_stmt.bnf
new file mode 100644
index 000000000000..ee632ac76569
--- /dev/null
+++ b/docs/generated/sql/bnf/routine_return_stmt.bnf
@@ -0,0 +1,2 @@
+routine_return_stmt ::=
+	'RETURN' a_expr
diff --git a/docs/generated/sql/bnf/stmt.bnf b/docs/generated/sql/bnf/stmt.bnf
index e8e556311237..7ccaafdc0f5b 100644
--- a/docs/generated/sql/bnf/stmt.bnf
+++ b/docs/generated/sql/bnf/stmt.bnf
@@ -1,23 +1,4 @@
 stmt ::=
 	'HELPTOKEN'
-	| preparable_stmt
-	| analyze_stmt
-	| copy_from_stmt
-	| comment_stmt
-	| execute_stmt
-	| deallocate_stmt
-	| discard_stmt
-	| grant_stmt
-	| prepare_stmt
-	| revoke_stmt
-	| savepoint_stmt
-	| reassign_owned_by_stmt
-	| drop_owned_by_stmt
-	| release_stmt
-	| refresh_stmt
-	| nonpreparable_set_stmt
-	| transaction_stmt
-	| close_cursor_stmt
-	| declare_cursor_stmt
-	| fetch_cursor_stmt
-	| move_cursor_stmt
+	| stmt_without_legacy_transaction
+	| legacy_transaction_stmt
diff --git a/docs/generated/sql/bnf/stmt_block.bnf b/docs/generated/sql/bnf/stmt_block.bnf
index 46f1299fb6b6..239cddd67599 100644
--- a/docs/generated/sql/bnf/stmt_block.bnf
+++ b/docs/generated/sql/bnf/stmt_block.bnf
@@ -3,7 +3,12 @@ stmt_block ::=
 
 stmt ::=
 	'HELPTOKEN'
-	| preparable_stmt
+	| stmt_without_legacy_transaction
+	| legacy_transaction_stmt
+	| 
+
+stmt_without_legacy_transaction ::=
+	preparable_stmt
 	| analyze_stmt
 	| copy_from_stmt
 	| comment_stmt
@@ -24,7 +29,10 @@ stmt ::=
 	| declare_cursor_stmt
 	| fetch_cursor_stmt
 	| move_cursor_stmt
-	| 
+
+legacy_transaction_stmt ::=
+	legacy_begin_stmt
+	| legacy_end_stmt
 
 preparable_stmt ::=
 	alter_stmt
@@ -140,6 +148,12 @@ fetch_cursor_stmt ::=
 move_cursor_stmt ::=
 	'MOVE' cursor_movement_specifier
 
+legacy_begin_stmt ::=
+	'BEGIN' opt_transaction begin_transaction
+
+legacy_end_stmt ::=
+	'END' opt_transaction
+
 alter_stmt ::=
 	alter_ddl_stmt
 	| alter_role_stmt
@@ -397,12 +411,10 @@ set_transaction_stmt ::=
 	| 'SET' 'SESSION' 'TRANSACTION' transaction_mode_list
 
 begin_stmt ::=
-	'BEGIN' opt_transaction begin_transaction
-	| 'START' 'TRANSACTION' begin_transaction
+	'START' 'TRANSACTION' begin_transaction
 
 commit_stmt ::=
 	'COMMIT' opt_transaction
-	| 'END' opt_transaction
 
 rollback_stmt ::=
 	'ROLLBACK' opt_transaction
@@ -445,6 +457,14 @@ cursor_movement_specifier ::=
 	| 'FIRST' opt_from_or_in cursor_name
 	| 'LAST' opt_from_or_in cursor_name
 
+opt_transaction ::=
+	'TRANSACTION'
+	| 
+
+begin_transaction ::=
+	transaction_mode_list
+	| 
+
 alter_ddl_stmt ::=
 	alter_table_stmt
 	| alter_index_stmt
@@ -528,6 +548,7 @@ create_ddl_stmt ::=
 	| create_type_stmt
 	| create_view_stmt
 	| create_sequence_stmt
+	| create_func_stmt
 
 create_stats_stmt ::=
 	'CREATE' 'STATISTICS' statistics_name opt_stats_columns 'FROM' create_stats_target opt_create_stats_options
@@ -927,6 +948,7 @@ unreserved_keyword ::=
 	| 'ALWAYS'
 	| 'ASENSITIVE'
 	| 'AT'
+	| 'ATOMIC'
 	| 'ATTRIBUTE'
 	| 'AUTOMATIC'
 	| 'AVAILABILITY'
@@ -940,6 +962,7 @@ unreserved_keyword ::=
 	| 'BUNDLE'
 	| 'BY'
 	| 'CACHE'
+	| 'CALLED'
 	| 'CANCEL'
 	| 'CANCELQUERY'
 	| 'CASCADE'
@@ -984,6 +1007,7 @@ unreserved_keyword ::=
 	| 'DELETE'
 	| 'DEFAULTS'
 	| 'DEFERRED'
+	| 'DEFINER'
 	| 'DELIMITER'
 	| 'DESTINATION'
 	| 'DETACHED'
@@ -1010,6 +1034,7 @@ unreserved_keyword ::=
 	| 'EXPLAIN'
 	| 'EXPORT'
 	| 'EXTENSION'
+	| 'EXTERNAL'
 	| 'FAILURE'
 	| 'FILES'
 	| 'FILTER'
@@ -1042,6 +1067,7 @@ unreserved_keyword ::=
 	| 'HOUR'
 	| 'IDENTITY'
 	| 'IMMEDIATE'
+	| 'IMMUTABLE'
 	| 'IMPORT'
 	| 'INCLUDE'
 	| 'INCLUDING'
@@ -1051,10 +1077,12 @@ unreserved_keyword ::=
 	| 'INDEXES'
 	| 'INHERITS'
 	| 'INJECT'
+	| 'INPUT'
 	| 'INSERT'
 	| 'INTO_DB'
 	| 'INVERTED'
 	| 'ISOLATION'
+	| 'INVOKER'
 	| 'JOB'
 	| 'JOBS'
 	| 'JSON'
@@ -1067,6 +1095,7 @@ unreserved_keyword ::=
 	| 'LATEST'
 	| 'LC_COLLATE'
 	| 'LC_CTYPE'
+	| 'LEAKPROOF'
 	| 'LEASE'
 	| 'LESS'
 	| 'LEVEL'
@@ -1144,6 +1173,7 @@ unreserved_keyword ::=
 	| 'OVER'
 	| 'OWNED'
 	| 'OWNER'
+	| 'PARALLEL'
 	| 'PARENT'
 	| 'PARTIAL'
 	| 'PARTITION'
@@ -1199,6 +1229,8 @@ unreserved_keyword ::=
 	| 'RESTRICTED'
 	| 'RESUME'
 	| 'RETRY'
+	| 'RETURN'
+	| 'RETURNS'
 	| 'REVISION_HISTORY'
 	| 'REVOKE'
 	| 'ROLE'
@@ -1223,6 +1255,7 @@ unreserved_keyword ::=
 	| 'SCRUB'
 	| 'SEARCH'
 	| 'SECOND'
+	| 'SECURITY'
 	| 'SERIALIZABLE'
 	| 'SEQUENCE'
 	| 'SEQUENCES'
@@ -1244,6 +1277,7 @@ unreserved_keyword ::=
 	| 'SPLIT'
 	| 'SQL'
 	| 'SQLLOGIN'
+	| 'STABLE'
 	| 'START'
 	| 'STATE'
 	| 'STATEMENTS'
@@ -1257,6 +1291,7 @@ unreserved_keyword ::=
 	| 'STRICT'
 	| 'SUBSCRIPTION'
 	| 'SUPER'
+	| 'SUPPORT'
 	| 'SURVIVE'
 	| 'SURVIVAL'
 	| 'SYNTAX'
@@ -1275,6 +1310,7 @@ unreserved_keyword ::=
 	| 'TRANSACTION'
 	| 'TRANSACTIONS'
 	| 'TRANSFER'
+	| 'TRANSFORM'
 	| 'TRIGGER'
 	| 'TRUNCATE'
 	| 'TRUSTED'
@@ -1301,6 +1337,7 @@ unreserved_keyword ::=
 	| 'VIEWACTIVITYREDACTED'
 	| 'VIEWCLUSTERSETTING'
 	| 'VISIBLE'
+	| 'VOLATILE'
 	| 'VOTERS'
 	| 'WITHIN'
 	| 'WITHOUT'
@@ -1332,6 +1369,7 @@ col_name_keyword ::=
 	| 'IF'
 	| 'IFERROR'
 	| 'IFNULL'
+	| 'INOUT'
 	| 'INT'
 	| 'INTEGER'
 	| 'INTERVAL'
@@ -1347,6 +1385,7 @@ col_name_keyword ::=
 	| 'PRECISION'
 	| 'REAL'
 	| 'ROW'
+	| 'SETOF'
 	| 'SMALLINT'
 	| 'STRING'
 	| 'SUBSTRING'
@@ -1397,14 +1436,6 @@ type_list ::=
 transaction_mode_list ::=
 	( transaction_mode ) ( ( opt_comma transaction_mode ) )*
 
-opt_transaction ::=
-	'TRANSACTION'
-	| 
-
-begin_transaction ::=
-	transaction_mode_list
-	| 
-
 opt_abort_mod ::=
 	'TRANSACTION'
 	| 'WORK'
@@ -1607,6 +1638,9 @@ create_sequence_stmt ::=
 	'CREATE' opt_temp 'SEQUENCE' sequence_name opt_sequence_option_list
 	| 'CREATE' opt_temp 'SEQUENCE' 'IF' 'NOT' 'EXISTS' sequence_name opt_sequence_option_list
 
+create_func_stmt ::=
+	'CREATE' opt_or_replace 'FUNCTION' func_create_name '(' opt_func_arg_with_default_list ')' 'RETURNS' opt_return_set func_return_type opt_create_func_opt_list opt_routine_body
+
 statistics_name ::=
 	name
 
@@ -2266,6 +2300,33 @@ opt_sequence_option_list ::=
 	sequence_option_list
 	| 
 
+opt_or_replace ::=
+	'OR' 'REPLACE'
+	| 
+
+func_create_name ::=
+	db_object_name
+
+opt_func_arg_with_default_list ::=
+	func_arg_with_default_list
+	| 
+
+opt_return_set ::=
+	'SETOF'
+	| 
+
+func_return_type ::=
+	func_arg_type
+
+opt_create_func_opt_list ::=
+	create_func_opt_list
+	| 
+
+opt_routine_body ::=
+	routine_return_stmt
+	| 'BEGIN' 'ATOMIC' routine_body_stmt_list 'END'
+	| 
+
 changefeed_target ::=
 	opt_table_prefix table_name opt_changefeed_family
 
@@ -2788,6 +2849,21 @@ create_as_table_defs ::=
 enum_val_list ::=
 	( 'SCONST' ) ( ( ',' 'SCONST' ) )*
 
+func_arg_with_default_list ::=
+	( func_arg_with_default ) ( ( ',' func_arg_with_default ) )*
+
+func_arg_type ::=
+	typename
+
+create_func_opt_list ::=
+	( create_func_opt_item ) ( ( create_func_opt_item ) )*
+
+routine_return_stmt ::=
+	'RETURN' a_expr
+
+routine_body_stmt_list ::=
+	(  ) ( ( routine_body_stmt ';' ) )*
+
 opt_table_prefix ::=
 	'TABLE'
 	| 
@@ -3157,6 +3233,20 @@ family_def ::=
 create_as_constraint_def ::=
 	create_as_constraint_elem
 
+func_arg_with_default ::=
+	func_arg
+	| func_arg 'DEFAULT' a_expr
+	| func_arg '=' a_expr
+
+create_func_opt_item ::=
+	'AS' func_as
+	| 'LANGUAGE' non_reserved_word_or_sconst
+	| common_func_opt_item
+
+routine_body_stmt ::=
+	stmt_without_legacy_transaction
+	| routine_return_stmt
+
 family_name ::=
 	name
 
@@ -3424,6 +3514,26 @@ opt_family_name ::=
 create_as_constraint_elem ::=
 	'PRIMARY' 'KEY' '(' create_as_params ')' opt_with_storage_parameter_list
 
+func_arg ::=
+	func_arg_class param_name func_arg_type
+	| param_name func_arg_class func_arg_type
+	| param_name func_arg_type
+	| func_arg_class func_arg_type
+	| func_arg_type
+
+func_as ::=
+	'SCONST'
+
+common_func_opt_item ::=
+	'CALLED' 'ON' 'NULL' 'INPUT'
+	| 'RETURNS' 'NULL' 'ON' 'NULL' 'INPUT'
+	| 'STRICT'
+	| 'IMMUTABLE'
+	| 'STABLE'
+	| 'VOLATILE'
+	| 'LEAKPROOF'
+	| 'NOT' 'LEAKPROOF'
+
 group_by_item ::=
 	a_expr
 
@@ -3505,6 +3615,12 @@ create_as_col_qualification_elem ::=
 create_as_params ::=
 	( create_as_param ) ( ( ',' create_as_param ) )*
 
+func_arg_class ::=
+	'IN'
+
+param_name ::=
+	type_function_name
+
 col_qualification ::=
 	'CONSTRAINT' constraint_name col_qualification_elem
 	| col_qualification_elem
diff --git a/docs/generated/sql/bnf/stmt_without_legacy_transaction.bnf b/docs/generated/sql/bnf/stmt_without_legacy_transaction.bnf
new file mode 100644
index 000000000000..efb2571bd1a6
--- /dev/null
+++ b/docs/generated/sql/bnf/stmt_without_legacy_transaction.bnf
@@ -0,0 +1,22 @@
+stmt_without_legacy_transaction ::=
+	preparable_stmt
+	| analyze_stmt
+	| copy_from_stmt
+	| comment_stmt
+	| execute_stmt
+	| deallocate_stmt
+	| discard_stmt
+	| grant_stmt
+	| prepare_stmt
+	| revoke_stmt
+	| savepoint_stmt
+	| reassign_owned_by_stmt
+	| drop_owned_by_stmt
+	| release_stmt
+	| refresh_stmt
+	| nonpreparable_set_stmt
+	| transaction_stmt
+	| close_cursor_stmt
+	| declare_cursor_stmt
+	| fetch_cursor_stmt
+	| move_cursor_stmt
diff --git a/pkg/gen/docs.bzl b/pkg/gen/docs.bzl
index 5281cb40e3d9..dbf599907e79 100644
--- a/pkg/gen/docs.bzl
+++ b/pkg/gen/docs.bzl
@@ -86,6 +86,7 @@ DOCS_SRCS = [
   "//docs/generated/sql/bnf:create_database_stmt.bnf",
   "//docs/generated/sql/bnf:create_ddl_stmt.bnf",
   "//docs/generated/sql/bnf:create_extension_stmt.bnf",
+  "//docs/generated/sql/bnf:create_func_stmt.bnf",
   "//docs/generated/sql/bnf:create_index_stmt.bnf",
   "//docs/generated/sql/bnf:create_inverted_index_stmt.bnf",
   "//docs/generated/sql/bnf:create_role_stmt.bnf",
@@ -138,6 +139,9 @@ DOCS_SRCS = [
   "//docs/generated/sql/bnf:insert_stmt.bnf",
   "//docs/generated/sql/bnf:iso_level.bnf",
   "//docs/generated/sql/bnf:joined_table.bnf",
+  "//docs/generated/sql/bnf:legacy_begin_stmt.bnf",
+  "//docs/generated/sql/bnf:legacy_end_stmt.bnf",
+  "//docs/generated/sql/bnf:legacy_transaction_stmt.bnf",
   "//docs/generated/sql/bnf:like_table_option_list.bnf",
   "//docs/generated/sql/bnf:limit_clause.bnf",
   "//docs/generated/sql/bnf:move_cursor_stmt.bnf",
@@ -175,6 +179,8 @@ DOCS_SRCS = [
   "//docs/generated/sql/bnf:resume_stmt.bnf",
   "//docs/generated/sql/bnf:revoke_stmt.bnf",
   "//docs/generated/sql/bnf:rollback_transaction.bnf",
+  "//docs/generated/sql/bnf:routine_body_stmt.bnf",
+  "//docs/generated/sql/bnf:routine_return_stmt.bnf",
   "//docs/generated/sql/bnf:row_source_extension_stmt.bnf",
   "//docs/generated/sql/bnf:savepoint_stmt.bnf",
   "//docs/generated/sql/bnf:scrub_database_stmt.bnf",
@@ -238,6 +244,7 @@ DOCS_SRCS = [
   "//docs/generated/sql/bnf:split_table_at.bnf",
   "//docs/generated/sql/bnf:stmt.bnf",
   "//docs/generated/sql/bnf:stmt_block.bnf",
+  "//docs/generated/sql/bnf:stmt_without_legacy_transaction.bnf",
   "//docs/generated/sql/bnf:table_clause.bnf",
   "//docs/generated/sql/bnf:table_constraint.bnf",
   "//docs/generated/sql/bnf:table_ref.bnf",
diff --git a/pkg/sql/logictest/testdata/logic_test/udf b/pkg/sql/logictest/testdata/logic_test/udf
new file mode 100644
index 000000000000..03cb98c91d11
--- /dev/null
+++ b/pkg/sql/logictest/testdata/logic_test/udf
@@ -0,0 +1,2 @@
+statement error pq: unimplemented: CREATE FUNCTION unimplemented
+CREATE OR REPLACE FUNCTION f(a int = 7) RETURNS INT AS 'SELECT 1' LANGUAGE SQL
diff --git a/pkg/sql/opt/optbuilder/builder.go b/pkg/sql/opt/optbuilder/builder.go
index 1cc7c6883e9e..069485ab7798 100644
--- a/pkg/sql/opt/optbuilder/builder.go
+++ b/pkg/sql/opt/optbuilder/builder.go
@@ -305,6 +305,10 @@ func (b *Builder) buildStmt(
 	case *tree.CreateView:
 		return b.buildCreateView(stmt, inScope)
 
+	case *tree.CreateFunction:
+		// TODO (Chengxiong): implement this
+		panic(unimplemented.NewWithIssue(83228, "CREATE FUNCTION unimplemented"))
+
 	case *tree.Explain:
 		return b.buildExplain(stmt, inScope)
 
diff --git a/pkg/sql/parser/parse.go b/pkg/sql/parser/parse.go
index 77b9f260b18b..5b884f45b2c4 100644
--- a/pkg/sql/parser/parse.go
+++ b/pkg/sql/parser/parse.go
@@ -152,13 +152,23 @@ func (p *Parser) scanOneStmt() (sql string, tokens []sqlSymType, done bool) {
 	// We make the resulting token positions match the returned string.
 	lval.pos = 0
 	tokens = append(tokens, lval)
+	var preValID int32
+	curFuncBodyCnt := 0
 	for {
 		if lval.id == ERROR {
 			return p.scanner.In()[startPos:], tokens, true
 		}
+		preValID = lval.id
 		posBeforeScan := p.scanner.Pos()
 		p.scanner.Scan(&lval)
-		if lval.id == 0 || lval.id == ';' {
+
+		if preValID == BEGIN && lval.id == ATOMIC {
+			curFuncBodyCnt++
+		}
+		if curFuncBodyCnt > 0 && lval.id == END {
+			curFuncBodyCnt--
+		}
+		if lval.id == 0 || (curFuncBodyCnt == 0 && lval.id == ';') {
 			return p.scanner.In()[startPos:posBeforeScan], tokens, (lval.id == 0)
 		}
 		lval.pos -= startPos
diff --git a/pkg/sql/parser/parse_test.go b/pkg/sql/parser/parse_test.go
index 05f741332e56..222b5c706b0b 100644
--- a/pkg/sql/parser/parse_test.go
+++ b/pkg/sql/parser/parse_test.go
@@ -421,8 +421,6 @@ func TestUnimplementedSyntax(t *testing.T) {
 		{`CREATE EXTENSION IF NOT EXISTS a WITH schema = 'public'`, 74777, `create extension if not exists with`, ``},
 		{`CREATE FOREIGN DATA WRAPPER a`, 0, `create fdw`, ``},
 		{`CREATE FOREIGN TABLE a`, 0, `create foreign table`, ``},
-		{`CREATE FUNCTION a`, 17511, `create`, ``},
-		{`CREATE OR REPLACE FUNCTION a`, 17511, `create`, ``},
 		{`CREATE LANGUAGE a`, 17511, `create language a`, ``},
 		{`CREATE OPERATOR a`, 65017, ``, ``},
 		{`CREATE PUBLICATION a`, 0, `create publication`, ``},
diff --git a/pkg/sql/parser/sql.y b/pkg/sql/parser/sql.y
index 48a44ab5c606..e022510a9f44 100644
--- a/pkg/sql/parser/sql.y
+++ b/pkg/sql/parser/sql.y
@@ -781,6 +781,27 @@ func (u *sqlSymUnion) cursorStmt() tree.CursorStmt {
 func (u *sqlSymUnion) asTenantClause() tree.TenantID {
     return u.val.(tree.TenantID)
 }
+func (u *sqlSymUnion) functionOptions() tree.FunctionOptions {
+    return u.val.(tree.FunctionOptions)
+}
+func (u *sqlSymUnion) functionOption() tree.FunctionOption {
+    return u.val.(tree.FunctionOption)
+}
+func (u *sqlSymUnion) functionArgs() tree.FuncArgs {
+    return u.val.(tree.FuncArgs)
+}
+func (u *sqlSymUnion) functionArg() tree.FuncArg {
+    return u.val.(tree.FuncArg)
+}
+func (u *sqlSymUnion) functionArgClass() tree.FuncArgClass {
+    return u.val.(tree.FuncArgClass)
+}
+func (u *sqlSymUnion) stmts() tree.Statements {
+    return u.val.(tree.Statements)
+}
+func (u *sqlSymUnion) routineBody() *tree.RoutineBody {
+    return u.val.(*tree.RoutineBody)
+}
 %}
 
 // NB: the %token definitions must come before the %type definitions in this
@@ -802,23 +823,23 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 // Ordinary key words in alphabetical order.
 %token <str> ABORT ABSOLUTE ACCESS ACTION ADD ADMIN AFTER AGGREGATE
 %token <str> ALL ALTER ALWAYS ANALYSE ANALYZE AND AND_AND ANY ANNOTATE_TYPE ARRAY AS ASC
-%token <str> ASENSITIVE ASYMMETRIC AT ATTRIBUTE AUTHORIZATION AUTOMATIC AVAILABILITY
+%token <str> ASENSITIVE ASYMMETRIC AT ATOMIC ATTRIBUTE AUTHORIZATION AUTOMATIC AVAILABILITY
 
 %token <str> BACKUP BACKUPS BACKWARD BEFORE BEGIN BETWEEN BIGINT BIGSERIAL BINARY BIT
 %token <str> BUCKET_COUNT
 %token <str> BOOLEAN BOTH BOX2D BUNDLE BY
 
-%token <str> CACHE CANCEL CANCELQUERY CASCADE CASE CAST CBRT CHANGEFEED CHAR
+%token <str> CACHE CALLED CANCEL CANCELQUERY CASCADE CASE CAST CBRT CHANGEFEED CHAR
 %token <str> CHARACTER CHARACTERISTICS CHECK CLOSE
 %token <str> CLUSTER COALESCE COLLATE COLLATION COLUMN COLUMNS COMMENT COMMENTS COMMIT
 %token <str> COMMITTED COMPACT COMPLETE COMPLETIONS CONCAT CONCURRENTLY CONFIGURATION CONFIGURATIONS CONFIGURE
 %token <str> CONFLICT CONNECTION CONSTRAINT CONSTRAINTS CONTAINS CONTROLCHANGEFEED CONTROLJOB
-%token <str> CONVERSION CONVERT COPY COVERING CREATE CREATEDB CREATELOGIN CREATEROLE
+%token <str> CONVERSION CONVERT COPY COST COVERING CREATE CREATEDB CREATELOGIN CREATEROLE
 %token <str> CROSS CSV CUBE CURRENT CURRENT_CATALOG CURRENT_DATE CURRENT_SCHEMA
 %token <str> CURRENT_ROLE CURRENT_TIME CURRENT_TIMESTAMP
 %token <str> CURRENT_USER CURSOR CYCLE
 
-%token <str> DATA DATABASE DATABASES DATE DAY DEBUG_PAUSE_ON DEC DECIMAL DEFAULT DEFAULTS
+%token <str> DATA DATABASE DATABASES DATE DAY DEBUG_PAUSE_ON DEC DECIMAL DEFAULT DEFAULTS DEFINER
 %token <str> DEALLOCATE DECLARE DEFERRABLE DEFERRED DELETE DELIMITER DESC DESTINATION DETACHED
 %token <str> DISCARD DISTINCT DO DOMAIN DOUBLE DROP
 
@@ -826,7 +847,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %token <str> EXISTS EXECUTE EXECUTION EXPERIMENTAL
 %token <str> EXPERIMENTAL_FINGERPRINTS EXPERIMENTAL_REPLICA
 %token <str> EXPERIMENTAL_AUDIT EXPERIMENTAL_RELOCATE
-%token <str> EXPIRATION EXPLAIN EXPORT EXTENSION EXTRACT EXTRACT_DURATION
+%token <str> EXPIRATION EXPLAIN EXPORT EXTENSION EXTERNAL EXTRACT EXTRACT_DURATION
 
 %token <str> FAILURE FALSE FAMILY FETCH FETCHVAL FETCHTEXT FETCHVAL_PATH FETCHTEXT_PATH
 %token <str> FILES FILTER
@@ -840,19 +861,19 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %token <str> HAVING HASH HEADER HIGH HISTOGRAM HOLD HOUR
 
 %token <str> IDENTITY
-%token <str> IF IFERROR IFNULL IGNORE_FOREIGN_KEYS ILIKE IMMEDIATE IMPORT IN INCLUDE
+%token <str> IF IFERROR IFNULL IGNORE_FOREIGN_KEYS ILIKE IMMEDIATE IMMUTABLE IMPORT IN INCLUDE
 %token <str> INCLUDING INCREMENT INCREMENTAL INCREMENTAL_LOCATION
 %token <str> INET INET_CONTAINED_BY_OR_EQUALS
 %token <str> INET_CONTAINS_OR_EQUALS INDEX INDEXES INHERITS INJECT INITIALLY
-%token <str> INNER INSENSITIVE INSERT INT INTEGER
-%token <str> INTERSECT INTERVAL INTO INTO_DB INVERTED IS ISERROR ISNULL ISOLATION
+%token <str> INNER INOUT INPUT INSENSITIVE INSERT INT INTEGER
+%token <str> INTERSECT INTERVAL INTO INTO_DB INVERTED INVOKER IS ISERROR ISNULL ISOLATION
 
 %token <str> JOB JOBS JOIN JSON JSONB JSON_SOME_EXISTS JSON_ALL_EXISTS
 
 %token <str> KEY KEYS KMS KV
 
 %token <str> LANGUAGE LAST LATERAL LATEST LC_CTYPE LC_COLLATE
-%token <str> LEADING LEASE LEAST LEFT LESS LEVEL LIKE LIMIT
+%token <str> LEADING LEASE LEAST LEAKPROOF LEFT LESS LEVEL LIKE LIMIT
 %token <str> LINESTRING LINESTRINGM LINESTRINGZ LINESTRINGZM
 %token <str> LIST LOCAL LOCALITY LOCALTIME LOCALTIMESTAMP LOCKED LOGIN LOOKUP LOW LSHIFT
 
@@ -869,7 +890,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %token <str> OF OFF OFFSET OID OIDS OIDVECTOR OLD_KMS ON ONLY OPT OPTION OPTIONS OR
 %token <str> ORDER ORDINALITY OTHERS OUT OUTER OVER OVERLAPS OVERLAY OWNED OWNER OPERATOR
 
-%token <str> PARENT PARTIAL PARTITION PARTITIONS PASSWORD PAUSE PAUSED PHYSICAL PLACEMENT PLACING
+%token <str> PARALLEL PARENT PARTIAL PARTITION PARTITIONS PASSWORD PAUSE PAUSED PHYSICAL PLACEMENT PLACING
 %token <str> PLAN PLANS POINT POINTM POINTZ POINTZM POLYGON POLYGONM POLYGONZ POLYGONZM
 %token <str> POSITION PRECEDING PRECISION PREPARE PRESERVE PRIMARY PRIOR PRIORITY PRIVILEGES
 %token <str> PROCEDURAL PUBLIC PUBLICATION
@@ -879,21 +900,21 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %token <str> RANGE RANGES READ REAL REASON REASSIGN RECURSIVE RECURRING REF REFERENCES REFRESH
 %token <str> REGCLASS REGION REGIONAL REGIONS REGNAMESPACE REGPROC REGPROCEDURE REGROLE REGTYPE REINDEX
 %token <str> RELATIVE RELOCATE REMOVE_PATH RENAME REPEATABLE REPLACE REPLICATION
-%token <str> RELEASE RESET RESTART RESTORE RESTRICT RESTRICTED RESUME RETURNING RETRY REVISION_HISTORY
+%token <str> RELEASE RESET RESTART RESTORE RESTRICT RESTRICTED RESUME RETURNING RETURN RETURNS RETRY REVISION_HISTORY
 %token <str> REVOKE RIGHT ROLE ROLES ROLLBACK ROLLUP ROUTINES ROW ROWS RSHIFT RULE RUNNING
 
-%token <str> SAVEPOINT SCANS SCATTER SCHEDULE SCHEDULES SCROLL SCHEMA SCHEMAS SCRUB SEARCH SECOND SELECT SEQUENCE SEQUENCES
-%token <str> SERIALIZABLE SERVER SESSION SESSIONS SESSION_USER SET SETS SETTING SETTINGS
+%token <str> SAVEPOINT SCANS SCATTER SCHEDULE SCHEDULES SCROLL SCHEMA SCHEMAS SCRUB SEARCH SECOND SECURITY SELECT SEQUENCE SEQUENCES
+%token <str> SERIALIZABLE SERVER SESSION SESSIONS SESSION_USER SET SETOF SETS SETTING SETTINGS
 %token <str> SHARE SHOW SIMILAR SIMPLE SKIP SKIP_LOCALITIES_CHECK SKIP_MISSING_FOREIGN_KEYS
 %token <str> SKIP_MISSING_SEQUENCES SKIP_MISSING_SEQUENCE_OWNERS SKIP_MISSING_VIEWS SMALLINT SMALLSERIAL SNAPSHOT SOME SPLIT SQL
 %token <str> SQLLOGIN
 
-%token <str> START STATE STATISTICS STATUS STDIN STREAM STRICT STRING STORAGE STORE STORED STORING SUBSTRING SUPER
-%token <str> SURVIVE SURVIVAL SYMMETRIC SYNTAX SYSTEM SQRT SUBSCRIPTION STATEMENTS
+%token <str> STABLE START STATE STATISTICS STATUS STDIN STREAM STRICT STRING STORAGE STORE STORED STORING SUBSTRING SUPER
+%token <str> SUPPORT SURVIVE SURVIVAL SYMMETRIC SYNTAX SYSTEM SQRT SUBSCRIPTION STATEMENTS
 
 %token <str> TABLE TABLES TABLESPACE TEMP TEMPLATE TEMPORARY TENANT TENANTS TESTING_RELOCATE TEXT THEN
 %token <str> TIES TIME TIMETZ TIMESTAMP TIMESTAMPTZ TO THROTTLING TRAILING TRACE
-%token <str> TRANSACTION TRANSACTIONS TRANSFER TREAT TRIGGER TRIM TRUE
+%token <str> TRANSACTION TRANSACTIONS TRANSFER TRANSFORM TREAT TRIGGER TRIM TRUE
 %token <str> TRUNCATE TRUSTED TYPE TYPES
 %token <str> TRACING
 
@@ -901,7 +922,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %token <str> UPDATE UPSERT UNSET UNTIL USE USER USERS USING UUID
 
 %token <str> VALID VALIDATE VALUE VALUES VARBIT VARCHAR VARIADIC VIEW VARYING VIEWACTIVITY VIEWACTIVITYREDACTED
-%token <str> VIEWCLUSTERSETTING VIRTUAL VISIBLE VOTERS
+%token <str> VIEWCLUSTERSETTING VIRTUAL VISIBLE VOLATILE VOTERS
 
 %token <str> WHEN WHERE WINDOW WITH WITHIN WITHOUT WORK WRITE
 
@@ -939,7 +960,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 }
 
 %type <tree.Statement> stmt_block
-%type <tree.Statement> stmt
+%type <tree.Statement> stmt stmt_without_legacy_transaction
 
 
 %type <tree.Statement> alter_stmt
@@ -1053,6 +1074,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %type <tree.Statement> create_table_as_stmt
 %type <tree.Statement> create_view_stmt
 %type <tree.Statement> create_sequence_stmt
+%type <tree.Statement> create_func_stmt
 
 %type <tree.Statement> create_stats_stmt
 %type <*tree.CreateStatsOptions> opt_create_stats_options
@@ -1163,7 +1185,7 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %type <str> session_var
 %type <*string> comment_text
 
-%type <tree.Statement> transaction_stmt
+%type <tree.Statement> transaction_stmt legacy_transaction_stmt legacy_begin_stmt legacy_end_stmt
 %type <tree.Statement> truncate_stmt
 %type <tree.Statement> update_stmt
 %type <tree.Statement> upsert_stmt
@@ -1495,6 +1517,19 @@ func (u *sqlSymUnion) asTenantClause() tree.TenantID {
 %type <privilege.TargetObjectType> target_object_type
 %type <tree.TenantID> opt_as_tenant_clause
 
+// User defined function relevant components.
+%type <bool> opt_or_replace opt_return_set
+%type <str> param_name func_as
+%type <tree.FuncArgs> opt_func_arg_with_default_list func_arg_with_default_list
+%type <tree.FuncArg> func_arg_with_default func_arg
+%type <tree.ResolvableTypeReference> func_return_type func_arg_type
+%type <tree.FunctionOptions> opt_create_func_opt_list create_func_opt_list
+%type <tree.FunctionOption> create_func_opt_item common_func_opt_item
+%type <tree.FuncArgClass> func_arg_class
+%type <*tree.UnresolvedObjectName> func_create_name
+%type <tree.Statement> routine_return_stmt routine_body_stmt
+%type <tree.Statements> routine_body_stmt_list
+%type <*tree.RoutineBody> opt_routine_body
 
 // Precedence: lowest to highest
 %nonassoc  VALUES              // see value_clause
@@ -1574,7 +1609,15 @@ stmt_block:
 
 stmt:
   HELPTOKEN { return helpWith(sqllex, "") }
-| preparable_stmt           // help texts in sub-rule
+| stmt_without_legacy_transaction
+| legacy_transaction_stmt
+| /* EMPTY */
+  {
+    $$.val = tree.Statement(nil)
+  }
+
+stmt_without_legacy_transaction:
+  preparable_stmt           // help texts in sub-rule
 | analyze_stmt              // EXTEND WITH HELP: ANALYZE
 | copy_from_stmt
 | comment_stmt
@@ -1596,10 +1639,6 @@ stmt:
 | fetch_cursor_stmt         // EXTEND WITH HELP: FETCH
 | move_cursor_stmt          // EXTEND WITH HELP: MOVE
 | reindex_stmt
-| /* EMPTY */
-  {
-    $$.val = tree.Statement(nil)
-  }
 
 // %Help: ALTER
 // %Category: Group
@@ -3797,6 +3836,251 @@ create_extension_stmt:
   }
 | CREATE EXTENSION error // SHOW HELP: CREATE EXTENSION
 
+create_func_stmt:
+  CREATE opt_or_replace FUNCTION func_create_name '(' opt_func_arg_with_default_list ')' RETURNS opt_return_set func_return_type
+  opt_create_func_opt_list opt_routine_body
+  {
+    name := $4.unresolvedObjectName().ToFunctionName()
+    $$.val = &tree.CreateFunction{
+      IsProcedure: false,
+      Replace: $2.bool(),
+      FuncName: name,
+      Args: $6.functionArgs(),
+      ReturnType: tree.FuncReturnType{
+        Type: $10.typeReference(),
+        IsSet: $9.bool(),
+      },
+      Options: $11.functionOptions(),
+      RoutineBody: $12.routineBody(),
+    }
+  }
+
+opt_or_replace:
+  OR REPLACE { $$.val = true }
+| /* EMPTY */ { $$.val = false }
+
+opt_return_set:
+  SETOF { $$.val = true}
+| /* EMPTY */ { $$.val = false }
+
+func_create_name:
+  db_object_name
+
+opt_func_arg_with_default_list:
+  func_arg_with_default_list { $$.val = $1.functionArgs() }
+| /* Empty */ { $$.val = tree.FuncArgs{} }
+
+func_arg_with_default_list:
+  func_arg_with_default { $$.val = tree.FuncArgs{$1.functionArg()} }
+| func_arg_with_default_list ',' func_arg_with_default { $$.val = append($1.functionArgs(), $3.functionArg()) }
+
+func_arg_with_default:
+  func_arg
+| func_arg DEFAULT a_expr
+  {
+    arg := $1.functionArg()
+    arg.DefaultVal = $3.expr()
+    $$.val = arg
+  }
+| func_arg '=' a_expr
+  {
+    arg := $1.functionArg()
+    arg.DefaultVal = $3.expr()
+    $$.val = arg
+  }
+
+func_arg:
+  func_arg_class param_name func_arg_type
+  {
+    $$.val = tree.FuncArg{
+      Name: tree.Name($2),
+      Type: $3.typeReference(),
+      Class: $1.functionArgClass(),
+    }
+  }
+| param_name func_arg_class func_arg_type
+  {
+    $$.val = tree.FuncArg{
+      Name: tree.Name($1),
+      Type: $3.typeReference(),
+      Class: $2.functionArgClass(),
+    }
+  }
+| param_name func_arg_type
+  {
+    $$.val = tree.FuncArg{
+      Name: tree.Name($1),
+      Type: $2.typeReference(),
+      Class: tree.FunctionArgIn,
+    }
+  }
+| func_arg_class func_arg_type
+  {
+    $$.val = tree.FuncArg{
+      Type: $2.typeReference(),
+      Class: $1.functionArgClass(),
+    }
+  }
+| func_arg_type
+  {
+    $$.val = tree.FuncArg{
+      Type: $1.typeReference(),
+      Class: tree.FunctionArgIn,
+    }
+  }
+
+func_arg_class:
+  IN { $$.val = tree.FunctionArgIn }
+| OUT { return unimplemented(sqllex, "create function with 'OUT' argument class") }
+| INOUT { return unimplemented(sqllex, "create function with 'INOUT' argument class") }
+| IN OUT { return unimplemented(sqllex, "create function with 'IN OUT' argument class") }
+| VARIADIC { return unimplemented(sqllex, "create function with 'VARIADIC' argument class") }
+
+func_arg_type:
+  typename
+
+func_return_type:
+  func_arg_type
+
+opt_create_func_opt_list:
+  create_func_opt_list { $$.val = $1.functionOptions() }
+| /* EMPTY */ { $$.val = tree.FunctionOptions{} }
+
+create_func_opt_list:
+  create_func_opt_item { $$.val = tree.FunctionOptions{$1.functionOption()} }
+| create_func_opt_list create_func_opt_item { $$.val = append($1.functionOptions(), $2.functionOption())}
+
+create_func_opt_item:
+  AS func_as
+  {
+    $$.val = tree.FunctionBodyStr($2)
+  }
+| LANGUAGE non_reserved_word_or_sconst
+  {
+    lang, err := tree.AsFunctionLanguage($2)
+    if err != nil {
+      return setErr(sqllex, err)
+    }
+    $$.val = lang
+  }
+| TRANSFORM { return unimplemented(sqllex, "create function...transform") }
+| WINDOW { return unimplemented(sqllex, "create function...window") }
+| common_func_opt_item
+  {
+    $$.val = $1.functionOption()
+  }
+
+common_func_opt_item:
+  CALLED ON NULL INPUT
+  {
+    $$.val = tree.FunctionCalledOnNullInput
+  }
+| RETURNS NULL ON NULL INPUT
+  {
+    $$.val = tree.FunctionReturnsNullOnNullInput
+  }
+| STRICT
+  {
+    $$.val = tree.FunctionStrict
+  }
+| IMMUTABLE
+  {
+    $$.val = tree.FunctionImmutable
+  }
+| STABLE
+  {
+    $$.val = tree.FunctionStable
+  }
+| VOLATILE
+  {
+    $$.val = tree.FunctionVolatile
+  }
+| EXTERNAL SECURITY DEFINER
+  {
+    return unimplemented(sqllex, "create function...security")
+  }
+| EXTERNAL SECURITY INVOKER
+  {
+    return unimplemented(sqllex, "create function...security")
+  }
+| SECURITY DEFINER
+  {
+    return unimplemented(sqllex, "create function...security")
+  }
+| SECURITY INVOKER
+  {
+    return unimplemented(sqllex, "create function...security")
+  }
+| LEAKPROOF
+  {
+    $$.val = tree.FunctionLeakProof(true)
+  }
+| NOT LEAKPROOF
+  {
+    $$.val = tree.FunctionLeakProof(false)
+  }
+| COST numeric_only
+  {
+    return unimplemented(sqllex, "create function...cost")
+  }
+| ROWS numeric_only
+  {
+    return unimplemented(sqllex, "create function...rows")
+  }
+| SUPPORT name
+  {
+    return unimplemented(sqllex, "create function...support")
+  }
+// In theory we should parse the a whole set/reset statement here. But it's fine
+// to just return fast on SET/RESET keyword for now since it's not supported
+// yet.
+| SET { return unimplemented(sqllex, "create function...set") }
+| RESET { return unimplemented(sqllex, "create function...reset") }
+| PARALLEL { return unimplemented(sqllex, "create function...parallel") }
+
+func_as:
+  SCONST
+
+routine_return_stmt:
+  RETURN a_expr
+{
+  $$.val = &tree.RoutineReturn{
+    ReturnVal: $2.expr(),
+  }
+}
+
+routine_body_stmt:
+  stmt_without_legacy_transaction
+| routine_return_stmt
+
+routine_body_stmt_list:
+  routine_body_stmt_list routine_body_stmt ';'
+  {
+    $$.val = append($1.stmts(), $2.stmt())
+  }
+| /* Empty */
+  {
+    $$.val = tree.Statements{}
+  }
+
+opt_routine_body:
+  routine_return_stmt
+  {
+    $$.val = &tree.RoutineBody{
+      Stmts: tree.Statements{$1.stmt()},
+    }
+  }
+| BEGIN ATOMIC routine_body_stmt_list END
+  {
+    $$.val = &tree.RoutineBody{
+        Stmts: $3.stmts(),
+    }
+  }
+| /* Empty */
+  {
+    $$.val = (*tree.RoutineBody)(nil)
+  }
+
 create_unsupported:
   CREATE ACCESS METHOD error { return unimplemented(sqllex, "create access method") }
 | CREATE AGGREGATE error { return unimplementedWithIssueDetail(sqllex, 74775, "create aggregate") }
@@ -3806,8 +4090,6 @@ create_unsupported:
 | CREATE DEFAULT CONVERSION error { return unimplemented(sqllex, "create def conv") }
 | CREATE FOREIGN TABLE error { return unimplemented(sqllex, "create foreign table") }
 | CREATE FOREIGN DATA error { return unimplemented(sqllex, "create fdw") }
-| CREATE FUNCTION error { return unimplementedWithIssueDetail(sqllex, 17511, "create function") }
-| CREATE OR REPLACE FUNCTION error { return unimplementedWithIssueDetail(sqllex, 17511, "create function") }
 | CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE name error { return unimplementedWithIssueDetail(sqllex, 17511, "create language " + $6) }
 | CREATE OPERATOR error { return unimplementedWithIssue(sqllex, 65017) }
 | CREATE PUBLICATION error { return unimplemented(sqllex, "create publication") }
@@ -3818,10 +4100,6 @@ create_unsupported:
 | CREATE TEXT error { return unimplementedWithIssueDetail(sqllex, 7821, "create text") }
 | CREATE TRIGGER error { return unimplementedWithIssueDetail(sqllex, 28296, "create trigger") }
 
-opt_or_replace:
-  OR REPLACE {}
-| /* EMPTY */ {}
-
 opt_trusted:
   TRUSTED {}
 | /* EMPTY */ {}
@@ -3862,6 +4140,7 @@ create_ddl_stmt:
 | create_type_stmt     // EXTEND WITH HELP: CREATE TYPE
 | create_view_stmt     // EXTEND WITH HELP: CREATE VIEW
 | create_sequence_stmt // EXTEND WITH HELP: CREATE SEQUENCE
+| create_func_stmt
 
 // %Help: CREATE STATISTICS - create a new table statistic
 // %Category: Misc
@@ -9388,12 +9667,7 @@ transaction_stmt:
 //
 // %SeeAlso: COMMIT, ROLLBACK, WEBDOCS/begin-transaction.html
 begin_stmt:
-  BEGIN opt_transaction begin_transaction
-  {
-    $$.val = $3.stmt()
-  }
-| BEGIN error // SHOW HELP: BEGIN
-| START TRANSACTION begin_transaction
+  START TRANSACTION begin_transaction
   {
     $$.val = $3.stmt()
   }
@@ -9411,11 +9685,6 @@ commit_stmt:
     $$.val = &tree.CommitTransaction{}
   }
 | COMMIT error // SHOW HELP: COMMIT
-| END opt_transaction
-  {
-    $$.val = &tree.CommitTransaction{}
-  }
-| END error // SHOW HELP: COMMIT
 
 abort_stmt:
   ABORT opt_abort_mod
@@ -9445,6 +9714,25 @@ rollback_stmt:
   }
 | ROLLBACK error // SHOW HELP: ROLLBACK
 
+legacy_transaction_stmt:
+  legacy_begin_stmt // EXTEND WITH HELP: BEGIN
+| legacy_end_stmt // EXTEND WITH HELP: COMMIT
+
+legacy_begin_stmt:
+  BEGIN opt_transaction begin_transaction
+  {
+    $$.val = $3.stmt()
+  }
+| BEGIN error // SHOW HELP: BEGIN
+
+legacy_end_stmt:
+  END opt_transaction
+  {
+    $$.val = &tree.CommitTransaction{}
+  }
+| END error // SHOW HELP: COMMIT
+
+
 opt_transaction:
   TRANSACTION {}
 | /* EMPTY */ {}
@@ -14056,6 +14344,9 @@ type_function_name_no_crdb_extra:
 | unreserved_keyword
 | type_func_name_no_crdb_extra_keyword
 
+param_name:
+  type_function_name
+
 // Any not-fully-reserved word --- these names can be, eg, variable names.
 non_reserved_word:
   IDENT
@@ -14094,6 +14385,7 @@ unreserved_keyword:
 | ALWAYS
 | ASENSITIVE
 | AT
+| ATOMIC
 | ATTRIBUTE
 | AUTOMATIC
 | AVAILABILITY
@@ -14107,6 +14399,7 @@ unreserved_keyword:
 | BUNDLE
 | BY
 | CACHE
+| CALLED
 | CANCEL
 | CANCELQUERY
 | CASCADE
@@ -14151,6 +14444,7 @@ unreserved_keyword:
 | DELETE
 | DEFAULTS
 | DEFERRED
+| DEFINER
 | DELIMITER
 | DESTINATION
 | DETACHED
@@ -14177,6 +14471,7 @@ unreserved_keyword:
 | EXPLAIN
 | EXPORT
 | EXTENSION
+| EXTERNAL
 | FAILURE
 | FILES
 | FILTER
@@ -14209,6 +14504,7 @@ unreserved_keyword:
 | HOUR
 | IDENTITY
 | IMMEDIATE
+| IMMUTABLE
 | IMPORT
 | INCLUDE
 | INCLUDING
@@ -14218,10 +14514,12 @@ unreserved_keyword:
 | INDEXES
 | INHERITS
 | INJECT
+| INPUT
 | INSERT
 | INTO_DB
 | INVERTED
 | ISOLATION
+| INVOKER
 | JOB
 | JOBS
 | JSON
@@ -14234,6 +14532,7 @@ unreserved_keyword:
 | LATEST
 | LC_COLLATE
 | LC_CTYPE
+| LEAKPROOF
 | LEASE
 | LESS
 | LEVEL
@@ -14311,6 +14610,7 @@ unreserved_keyword:
 | OVER
 | OWNED
 | OWNER
+| PARALLEL
 | PARENT
 | PARTIAL
 | PARTITION
@@ -14366,6 +14666,8 @@ unreserved_keyword:
 | RESTRICTED
 | RESUME
 | RETRY
+| RETURN
+| RETURNS
 | REVISION_HISTORY
 | REVOKE
 | ROLE
@@ -14390,6 +14692,7 @@ unreserved_keyword:
 | SCRUB
 | SEARCH
 | SECOND
+| SECURITY
 | SERIALIZABLE
 | SEQUENCE
 | SEQUENCES
@@ -14411,6 +14714,7 @@ unreserved_keyword:
 | SPLIT
 | SQL
 | SQLLOGIN
+| STABLE
 | START
 | STATE
 | STATEMENTS
@@ -14424,6 +14728,7 @@ unreserved_keyword:
 | STRICT
 | SUBSCRIPTION
 | SUPER
+| SUPPORT
 | SURVIVE
 | SURVIVAL
 | SYNTAX
@@ -14442,6 +14747,7 @@ unreserved_keyword:
 | TRANSACTION
 | TRANSACTIONS
 | TRANSFER
+| TRANSFORM
 | TRIGGER
 | TRUNCATE
 | TRUSTED
@@ -14468,6 +14774,7 @@ unreserved_keyword:
 | VIEWACTIVITYREDACTED
 | VIEWCLUSTERSETTING
 | VISIBLE
+| VOLATILE
 | VOTERS
 | WITHIN
 | WITHOUT
@@ -14508,6 +14815,7 @@ col_name_keyword:
 | IF
 | IFERROR
 | IFNULL
+| INOUT
 | INT
 | INTEGER
 | INTERVAL
@@ -14523,6 +14831,7 @@ col_name_keyword:
 | PRECISION
 | REAL
 | ROW
+| SETOF
 | SMALLINT
 | STRING
 | SUBSTRING
diff --git a/pkg/sql/parser/testdata/create_function b/pkg/sql/parser/testdata/create_function
new file mode 100644
index 000000000000..7025a24e94b8
--- /dev/null
+++ b/pkg/sql/parser/testdata/create_function
@@ -0,0 +1,73 @@
+parse
+CREATE OR REPLACE FUNCTION f(a int = 7) RETURNS INT AS 'SELECT 1' LANGUAGE SQL
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT 7) RETURNS INT8 LANGUAGE SQL AS $$SELECT 1$$ -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT (7)) RETURNS INT8 LANGUAGE SQL AS $$SELECT 1$$ -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT _) RETURNS INT8 LANGUAGE SQL AS $$SELECT 1$$ -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8 DEFAULT 7) RETURNS INT8 LANGUAGE SQL AS $$SELECT 1$$ -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(IN a INT=7) RETURNS INT CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS 'SELECT 1'
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT 7) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT (7)) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT _) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8 DEFAULT 7) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(IN a INT=7) RETURNS INT AS 'SELECT 1' CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT 7) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT (7)) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT _) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8 DEFAULT 7) RETURNS INT8 CALLED ON NULL INPUT IMMUTABLE LEAKPROOF LANGUAGE SQL AS $$SELECT 1$$ -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(a INT DEFAULT 10) RETURNS INT RETURNS NULL ON NULL INPUT LANGUAGE SQL AS 'SELECT 1'
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT 10) RETURNS INT8 RETURNS NULL ON NULL INPUT LANGUAGE SQL AS $$SELECT 1$$ -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT (10)) RETURNS INT8 RETURNS NULL ON NULL INPUT LANGUAGE SQL AS $$SELECT 1$$ -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8 DEFAULT _) RETURNS INT8 RETURNS NULL ON NULL INPUT LANGUAGE SQL AS $$SELECT 1$$ -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8 DEFAULT 10) RETURNS INT8 RETURNS NULL ON NULL INPUT LANGUAGE SQL AS $$SELECT 1$$ -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT a; END
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT a; END -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT (1); SELECT (a); END -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT _; SELECT a; END -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT _; END -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT $1; END
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT $1; END -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT (1); SELECT ($1); END -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT _; SELECT $1; END -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; SELECT $1; END -- identifiers removed
+
+parse
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1; CREATE OR REPLACE FUNCTION g() RETURNS INT BEGIN ATOMIC SELECT 2; END; END
+----
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; CREATE OR REPLACE FUNCTION g() RETURNS INT8 BEGIN ATOMIC SELECT 2; END; END -- normalized!
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT (1); CREATE OR REPLACE FUNCTION g() RETURNS INT8 BEGIN ATOMIC SELECT (2); END; END -- fully parenthesized
+CREATE OR REPLACE FUNCTION f(IN a INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT _; CREATE OR REPLACE FUNCTION g() RETURNS INT8 BEGIN ATOMIC SELECT _; END; END -- literals removed
+CREATE OR REPLACE FUNCTION _(IN _ INT8) RETURNS INT8 LANGUAGE SQL BEGIN ATOMIC SELECT 1; CREATE OR REPLACE FUNCTION _() RETURNS INT8 BEGIN ATOMIC SELECT 2; END; END -- identifiers removed
+
+error
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1 END
+----
+at or near "end": syntax error
+DETAIL: source SQL:
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1 END
+                                                                                   ^
+HINT: try \h CREATE
+
+error
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1; CREATE OR REPLACE FUNCTION g() RETURNS INT BEGIN ATOMIC SELECT 2; END;
+----
+at or near "EOF": syntax error
+DETAIL: source SQL:
+CREATE OR REPLACE FUNCTION f(a INT) RETURNS INT LANGUAGE SQL BEGIN ATOMIC SELECT 1; CREATE OR REPLACE FUNCTION g() RETURNS INT BEGIN ATOMIC SELECT 2; END;
+                                                                                                                                                          ^
+HINT: try \h CREATE
diff --git a/pkg/sql/scanner/scan.go b/pkg/sql/scanner/scan.go
index ed303af6c22f..b590b9136650 100644
--- a/pkg/sql/scanner/scan.go
+++ b/pkg/sql/scanner/scan.go
@@ -1038,12 +1038,21 @@ func (s *Scanner) scanOne(lval *fakeSym) (done, hasToks bool, err error) {
 		}
 	}
 
+	var preValID int32
+	curFuncBodyCnt := 0
 	for {
 		if lval.id == lexbase.ERROR {
 			return true, true, fmt.Errorf("scan error: %s", lval.s)
 		}
+		preValID = lval.id
 		s.Scan(lval)
-		if lval.id == 0 || lval.id == ';' {
+		if preValID == lexbase.BEGIN && lval.id == lexbase.ATOMIC {
+			curFuncBodyCnt++
+		}
+		if curFuncBodyCnt > 0 && lval.id == lexbase.END {
+			curFuncBodyCnt--
+		}
+		if lval.id == 0 || (curFuncBodyCnt == 0 && lval.id == ';') {
 			return (lval.id == 0), true, nil
 		}
 	}
diff --git a/pkg/sql/sem/tree/BUILD.bazel b/pkg/sql/sem/tree/BUILD.bazel
index 5716e63d179a..74edb0590bf7 100644
--- a/pkg/sql/sem/tree/BUILD.bazel
+++ b/pkg/sql/sem/tree/BUILD.bazel
@@ -100,6 +100,7 @@ go_library(
         "type_check.go",
         "type_name.go",
         "typing.go",
+        "udf.go",
         "union.go",
         "unsupported_error.go",
         "update.go",
diff --git a/pkg/sql/sem/tree/object_name.go b/pkg/sql/sem/tree/object_name.go
index 52f706bf3c10..1a7797bf270f 100644
--- a/pkg/sql/sem/tree/object_name.go
+++ b/pkg/sql/sem/tree/object_name.go
@@ -205,13 +205,11 @@ func (u *UnresolvedObjectName) Format(ctx *FmtCtx) {
 
 func (u *UnresolvedObjectName) String() string { return AsString(u) }
 
-// ToTableName converts the unresolved name to a table name.
-//
 // TODO(radu): the schema and catalog names might not be in the right places; we
 // would only figure that out during name resolution. This method is temporary,
 // while we change all the code paths to only use TableName after resolution.
-func (u *UnresolvedObjectName) ToTableName() TableName {
-	return TableName{objName{
+func (u *UnresolvedObjectName) toObjName() objName {
+	return objName{
 		ObjectName: Name(u.Parts[0]),
 		ObjectNamePrefix: ObjectNamePrefix{
 			SchemaName:      Name(u.Parts[1]),
@@ -219,7 +217,17 @@ func (u *UnresolvedObjectName) ToTableName() TableName {
 			ExplicitSchema:  u.NumParts >= 2,
 			ExplicitCatalog: u.NumParts >= 3,
 		},
-	}}
+	}
+}
+
+// ToTableName converts the unresolved name to a table name.
+func (u *UnresolvedObjectName) ToTableName() TableName {
+	return TableName{u.toObjName()}
+}
+
+// ToFunctionName converts the unresolved name to a function name.
+func (u *UnresolvedObjectName) ToFunctionName() FunctionName {
+	return FunctionName{u.toObjName()}
 }
 
 // ToUnresolvedName converts the unresolved object name to the more general
diff --git a/pkg/sql/sem/tree/stmt.go b/pkg/sql/sem/tree/stmt.go
index 9c703d9bd973..155f49c6cd58 100644
--- a/pkg/sql/sem/tree/stmt.go
+++ b/pkg/sql/sem/tree/stmt.go
@@ -85,6 +85,9 @@ const (
 	TypeTCL
 )
 
+// Statements represent a list of statements.
+type Statements []Statement
+
 // Statement represents a statement.
 type Statement interface {
 	fmt.Stringer
@@ -1779,6 +1782,24 @@ func (*ValuesClause) StatementType() StatementType { return TypeDML }
 // StatementTag returns a short string identifying the type of statement.
 func (*ValuesClause) StatementTag() string { return "VALUES" }
 
+// StatementReturnType implements the Statement interface.
+func (*CreateFunction) StatementReturnType() StatementReturnType { return DDL }
+
+// StatementType implements the Statement interface.
+func (*CreateFunction) StatementType() StatementType { return TypeDDL }
+
+// StatementTag returns a short string identifying the type of statement.
+func (*CreateFunction) StatementTag() string { return "CREATE FUNCTION" }
+
+// StatementReturnType implements the Statement interface.
+func (*RoutineReturn) StatementReturnType() StatementReturnType { return Rows }
+
+// StatementType implements the Statement interface.
+func (*RoutineReturn) StatementType() StatementType { return TypeDML }
+
+// StatementTag returns a short string identifying the type of statement.
+func (*RoutineReturn) StatementTag() string { return "RETURN" }
+
 func (n *AlterChangefeed) String() string                { return AsString(n) }
 func (n *AlterChangefeedCmds) String() string            { return AsString(n) }
 func (n *AlterBackup) String() string                    { return AsString(n) }
@@ -1836,6 +1857,7 @@ func (n *CopyFrom) String() string                       { return AsString(n) }
 func (n *CreateChangefeed) String() string               { return AsString(n) }
 func (n *CreateDatabase) String() string                 { return AsString(n) }
 func (n *CreateExtension) String() string                { return AsString(n) }
+func (n *CreateFunction) String() string                 { return AsString(n) }
 func (n *CreateIndex) String() string                    { return AsString(n) }
 func (n *CreateRole) String() string                     { return AsString(n) }
 func (n *CreateTable) String() string                    { return AsString(n) }
@@ -1878,6 +1900,7 @@ func (n *ReparentDatabase) String() string               { return AsString(n) }
 func (n *RenameIndex) String() string                    { return AsString(n) }
 func (n *RenameTable) String() string                    { return AsString(n) }
 func (n *Restore) String() string                        { return AsString(n) }
+func (n *RoutineReturn) String() string                  { return AsString(n) }
 func (n *Revoke) String() string                         { return AsString(n) }
 func (n *RevokeRole) String() string                     { return AsString(n) }
 func (n *RollbackToSavepoint) String() string            { return AsString(n) }
diff --git a/pkg/sql/sem/tree/udf.go b/pkg/sql/sem/tree/udf.go
new file mode 100644
index 000000000000..f7181e9ee223
--- /dev/null
+++ b/pkg/sql/sem/tree/udf.go
@@ -0,0 +1,291 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package tree
+
+import (
+	"strings"
+
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
+	"github.com/cockroachdb/errors"
+)
+
+// FunctionName represent a function name in a UDF relevant statement, either
+// DDL or DML statement. Similar to TableName, it is constructed for incoming
+// SQL queries from an UnresolvedObjectName.
+type FunctionName struct {
+	objName
+}
+
+// Format implements the NodeFormatter interface.
+func (f *FunctionName) Format(ctx *FmtCtx) {
+	f.ObjectNamePrefix.Format(ctx)
+	if f.ExplicitSchema || ctx.alwaysFormatTablePrefix() {
+		ctx.WriteByte('.')
+	}
+	ctx.FormatNode(&f.ObjectName)
+}
+
+// CreateFunction represents a CREATE FUNCTION statement.
+type CreateFunction struct {
+	IsProcedure bool
+	Replace     bool
+	FuncName    FunctionName
+	Args        FuncArgs
+	ReturnType  FuncReturnType
+	Options     FunctionOptions
+	RoutineBody *RoutineBody
+}
+
+// Format implements the NodeFormatter interface.
+func (node *CreateFunction) Format(ctx *FmtCtx) {
+	ctx.WriteString("CREATE ")
+	if node.Replace {
+		ctx.WriteString("OR REPLACE ")
+	}
+	ctx.WriteString("FUNCTION ")
+	ctx.FormatNode(&node.FuncName)
+	ctx.WriteString("(")
+	ctx.FormatNode(node.Args)
+	ctx.WriteString(") ")
+	ctx.WriteString("RETURNS ")
+	if node.ReturnType.IsSet {
+		ctx.WriteString("SETOF ")
+	}
+	ctx.WriteString(node.ReturnType.Type.SQLString())
+	ctx.WriteString(" ")
+	var funcBody FunctionBodyStr
+	for _, option := range node.Options {
+		switch t := option.(type) {
+		case FunctionBodyStr:
+			funcBody = t
+			continue
+		}
+		ctx.FormatNode(option)
+		ctx.WriteString(" ")
+	}
+	if len(funcBody) > 0 {
+		ctx.FormatNode(funcBody)
+	}
+	if node.RoutineBody != nil {
+		ctx.WriteString("BEGIN ATOMIC ")
+		for _, stmt := range node.RoutineBody.Stmts {
+			ctx.FormatNode(stmt)
+			ctx.WriteString("; ")
+		}
+		ctx.WriteString("END")
+	}
+}
+
+// RoutineBody represent a list of statements in a UDF body.
+type RoutineBody struct {
+	Stmts Statements
+}
+
+// RoutineReturn represent a RETURN statement in a UDF body.
+type RoutineReturn struct {
+	ReturnVal Expr
+}
+
+// Format implements the NodeFormatter interface.
+func (node *RoutineReturn) Format(ctx *FmtCtx) {
+	ctx.WriteString("RETURN ")
+	ctx.FormatNode(node.ReturnVal)
+}
+
+// FunctionOptions represent a list of function options.
+type FunctionOptions []FunctionOption
+
+// FunctionOption is an interface representing UDF properties.
+type FunctionOption interface {
+	functionOption()
+	NodeFormatter
+}
+
+func (FunctionNullInputBehavior) functionOption() {}
+func (FunctionVolatility) functionOption()        {}
+func (FunctionLeakProof) functionOption()         {}
+func (FunctionBodyStr) functionOption()           {}
+func (FunctionLanguage) functionOption()          {}
+
+// FunctionNullInputBehavior represent UDF property on null parameters.
+type FunctionNullInputBehavior int
+
+const (
+	// FunctionCalledOnNullInput indicates that the function will be given the
+	// chance to execute when presented with NULL input.
+	FunctionCalledOnNullInput FunctionNullInputBehavior = iota
+	// FunctionReturnsNullOnNullInput indicates that the function will result in
+	// NULL given any NULL parameter.
+	FunctionReturnsNullOnNullInput
+	// FunctionStrict is the same as FunctionReturnsNullOnNullInput
+	FunctionStrict
+)
+
+// Format implements the NodeFormatter interface.
+func (node FunctionNullInputBehavior) Format(ctx *FmtCtx) {
+	switch node {
+	case FunctionCalledOnNullInput:
+		ctx.WriteString("CALLED ON NULL INPUT")
+	case FunctionReturnsNullOnNullInput:
+		ctx.WriteString("RETURNS NULL ON NULL INPUT")
+	case FunctionStrict:
+		ctx.WriteString("STRICT")
+	default:
+		panic(pgerror.New(pgcode.InvalidParameterValue, "Unknown function option"))
+	}
+}
+
+// FunctionVolatility represent UDF volatility property.
+type FunctionVolatility int
+
+const (
+	// FunctionVolatile see volatility.Volatile
+	FunctionVolatile FunctionVolatility = iota
+	// FunctionImmutable see volatility.Immutable
+	FunctionImmutable
+	// FunctionStable see volatility.Stable
+	FunctionStable
+)
+
+// Format implements the NodeFormatter interface.
+func (node FunctionVolatility) Format(ctx *FmtCtx) {
+	switch node {
+	case FunctionVolatile:
+		ctx.WriteString("VOLATILE")
+	case FunctionImmutable:
+		ctx.WriteString("IMMUTABLE")
+	case FunctionStable:
+		ctx.WriteString("STABLE")
+	default:
+		panic(pgerror.New(pgcode.InvalidParameterValue, "Unknown function option"))
+	}
+}
+
+// FunctionLeakProof indicates whether if a UDF is leakproof or not.
+type FunctionLeakProof bool
+
+// Format implements the NodeFormatter interface.
+func (node FunctionLeakProof) Format(ctx *FmtCtx) {
+	if !node {
+		ctx.WriteString("NOT ")
+	}
+	ctx.WriteString("LEAKPROOF")
+}
+
+// FunctionLanguage indicates the language of the statements in the UDF function
+// body.
+type FunctionLanguage int
+
+const (
+	_ FunctionLanguage = iota
+	// FunctionLangSQL represent SQL language.
+	FunctionLangSQL
+)
+
+// Format implements the NodeFormatter interface.
+func (node FunctionLanguage) Format(ctx *FmtCtx) {
+	ctx.WriteString("LANGUAGE ")
+	switch node {
+	case FunctionLangSQL:
+		ctx.WriteString("SQL")
+	default:
+		panic(pgerror.New(pgcode.InvalidParameterValue, "Unknown function option"))
+	}
+}
+
+// AsFunctionLanguage converts a string to a FunctionLanguage if applicable.
+// Error is returned if string does not represent a valid UDF language.
+func AsFunctionLanguage(lang string) (FunctionLanguage, error) {
+	switch strings.ToLower(lang) {
+	case "sql":
+		return FunctionLangSQL, nil
+	}
+	return 0, errors.Newf("language %q does not exist", lang)
+}
+
+// FunctionBodyStr is a string containing all statements in a UDF body.
+type FunctionBodyStr string
+
+// Format implements the NodeFormatter interface.
+func (node FunctionBodyStr) Format(ctx *FmtCtx) {
+	ctx.WriteString("AS ")
+	ctx.WriteString("$$")
+	ctx.WriteString(string(node))
+	ctx.WriteString("$$")
+}
+
+// FuncArgs represents a list of FuncArg.
+type FuncArgs []FuncArg
+
+// Format implements the NodeFormatter interface.
+func (node FuncArgs) Format(ctx *FmtCtx) {
+	for i, arg := range node {
+		if i > 0 {
+			ctx.WriteString(", ")
+		}
+		ctx.FormatNode(&arg)
+	}
+}
+
+// FuncArg represents an argument from a UDF signature.
+type FuncArg struct {
+	Name       Name
+	Type       ResolvableTypeReference
+	Class      FuncArgClass
+	DefaultVal Expr
+}
+
+// Format implements the NodeFormatter interface.
+func (node *FuncArg) Format(ctx *FmtCtx) {
+	switch node.Class {
+	case FunctionArgIn:
+		ctx.WriteString("IN")
+	case FunctionArgOut:
+		ctx.WriteString("OUT")
+	case FunctionArgInOut:
+		ctx.WriteString("INOUT")
+	case FunctionArgVariadic:
+		ctx.WriteString("VARIADIC")
+	default:
+		panic(pgerror.New(pgcode.InvalidParameterValue, "Unknown function option"))
+	}
+	ctx.WriteString(" ")
+	if node.Name != "" {
+		ctx.FormatNode(&node.Name)
+		ctx.WriteString(" ")
+	}
+	ctx.WriteString(node.Type.SQLString())
+	if node.DefaultVal != nil {
+		ctx.WriteString(" DEFAULT ")
+		ctx.FormatNode(node.DefaultVal)
+	}
+}
+
+// FuncArgClass indicates what type of argument an arg is.
+type FuncArgClass int
+
+const (
+	// FunctionArgIn args can only be used as input.
+	FunctionArgIn FuncArgClass = iota
+	// FunctionArgOut args can only be used as output.
+	FunctionArgOut
+	// FunctionArgInOut args can be used as both input and output.
+	FunctionArgInOut
+	// FunctionArgVariadic args are variadic.
+	FunctionArgVariadic
+)
+
+// FuncReturnType represent the return type of UDF.
+type FuncReturnType struct {
+	Type  ResolvableTypeReference
+	IsSet bool
+}