From f7835f44b76d712d8c77aa15438481783623581e Mon Sep 17 00:00:00 2001
From: Adam Pantel <adam@cockroachlabs.com>
Date: Tue, 3 Mar 2020 14:33:24 -0500
Subject: [PATCH] Add close cursor statement

Release note (sql): Adds syntax for DECLARE and CLOSE. CLOSE ALL is a no-op, as there are no cursors to close. CLOSE <cursor> and DECLARE raise unimplemented errors.
---
 docs/generated/sql/bnf/stmt_block.bnf |  6 ++++++
 pkg/sql/parser/sql.y                  | 24 +++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/docs/generated/sql/bnf/stmt_block.bnf b/docs/generated/sql/bnf/stmt_block.bnf
index 2b778f2d454d..4b14c2b23cfd 100644
--- a/docs/generated/sql/bnf/stmt_block.bnf
+++ b/docs/generated/sql/bnf/stmt_block.bnf
@@ -16,6 +16,7 @@ stmt ::=
 	| release_stmt
 	| nonpreparable_set_stmt
 	| transaction_stmt
+	| close_cursor_stmt
 	| 
 
 preparable_stmt ::=
@@ -90,6 +91,9 @@ transaction_stmt ::=
 	| rollback_stmt
 	| abort_stmt
 
+close_cursor_stmt ::=
+	'CLOSE' 'ALL'
+
 alter_stmt ::=
 	alter_ddl_stmt
 	| alter_user_stmt
@@ -642,6 +646,7 @@ unreserved_keyword ::=
 	| 'CANCEL'
 	| 'CASCADE'
 	| 'CHANGEFEED'
+	| 'CLOSE'
 	| 'CLUSTER'
 	| 'COLUMNS'
 	| 'COMMENT'
@@ -667,6 +672,7 @@ unreserved_keyword ::=
 	| 'DATE'
 	| 'DAY'
 	| 'DEALLOCATE'
+	| 'DECLARE'
 	| 'DELETE'
 	| 'DEFERRED'
 	| 'DISCARD'
diff --git a/pkg/sql/parser/sql.y b/pkg/sql/parser/sql.y
index c507449fef98..0f5b0f65a89b 100644
--- a/pkg/sql/parser/sql.y
+++ b/pkg/sql/parser/sql.y
@@ -530,7 +530,7 @@ func newNameFromStr(s string) *tree.Name {
 %token <str> BLOB BOOL BOOLEAN BOTH BY BYTEA BYTES
 
 %token <str> CACHE CANCEL CASCADE CASE CAST CHANGEFEED CHAR
-%token <str> CHARACTER CHARACTERISTICS CHECK
+%token <str> CHARACTER CHARACTERISTICS CHECK CLOSE
 %token <str> CLUSTER COALESCE COLLATE COLLATION COLUMN COLUMNS COMMENT COMMIT
 %token <str> COMMITTED COMPACT COMPLETE CONCAT CONFIGURATION CONFIGURATIONS CONFIGURE
 %token <str> CONFLICT CONSTRAINT CONSTRAINTS CONTAINS CONVERSION COPY COVERING CREATE CREATEROLE
@@ -539,7 +539,7 @@ func newNameFromStr(s string) *tree.Name {
 %token <str> CURRENT_USER CYCLE
 
 %token <str> DATA DATABASE DATABASES DATE DAY DEC DECIMAL DEFAULT
-%token <str> DEALLOCATE DEFERRABLE DEFERRED DELETE DESC
+%token <str> DEALLOCATE DECLARE DEFERRABLE DEFERRED DELETE DESC
 %token <str> DISCARD DISTINCT DO DOMAIN DOUBLE DROP
 
 %token <str> ELSE ENCODING END ENUM ESCAPE EXCEPT EXCLUDE
@@ -807,6 +807,9 @@ func newNameFromStr(s string) *tree.Name {
 %type <tree.Statement> upsert_stmt
 %type <tree.Statement> use_stmt
 
+%type <tree.Statement> close_cursor_stmt
+%type <tree.Statement> declare_cursor_stmt
+
 %type <[]string> opt_incremental
 %type <tree.KVOption> kv_option
 %type <[]tree.KVOption> kv_option_list opt_with_options var_set_list
@@ -849,7 +852,7 @@ func newNameFromStr(s string) *tree.Name {
 %type <*tree.UnresolvedName> func_name
 %type <str> opt_collate
 
-%type <str> database_name index_name opt_index_name column_name insert_column_item statistics_name window_name
+%type <str> cursor_name database_name index_name opt_index_name column_name insert_column_item statistics_name window_name
 %type <str> family_name opt_family_name table_alias_name constraint_name target_name zone_name partition_name collation_name
 %type <str> db_object_name_component
 %type <*tree.UnresolvedObjectName> table_name standalone_index_name sequence_name type_name view_name db_object_name simple_db_object_name complex_db_object_name
@@ -1140,6 +1143,8 @@ stmt:
 | release_stmt      // EXTEND WITH HELP: RELEASE
 | nonpreparable_set_stmt // help texts in sub-rule
 | transaction_stmt  // help texts in sub-rule
+| close_cursor_stmt
+| declare_cursor_stmt
 | /* EMPTY */
   {
     $$.val = tree.Statement(nil)
@@ -3399,6 +3404,15 @@ show_stmt:
 | show_zone_stmt
 | SHOW error                // SHOW HELP: SHOW
 
+// Cursors are not yet supported by CockroachDB. CLOSE ALL is safe to no-op
+// since there will be no open cursors.
+close_cursor_stmt:
+	CLOSE ALL { }
+| CLOSE cursor_name { return unimplementedWithIssue(sqllex, 41412) }
+
+declare_cursor_stmt:
+	DECLARE { return unimplementedWithIssue(sqllex, 41412) }
+
 // %Help: SHOW SESSION - display session variables
 // %Category: Cfg
 // %Text: SHOW [SESSION] { <var> | ALL }
@@ -9556,6 +9570,8 @@ standalone_index_name: db_object_name
 
 explain_option_name:   non_reserved_word
 
+cursor_name:           name
+
 // Names for column references.
 // Accepted patterns:
 // <colname>
@@ -9757,6 +9773,7 @@ unreserved_keyword:
 | CANCEL
 | CASCADE
 | CHANGEFEED
+| CLOSE
 | CLUSTER
 | COLUMNS
 | COMMENT
@@ -9782,6 +9799,7 @@ unreserved_keyword:
 | DATE
 | DAY
 | DEALLOCATE
+| DECLARE
 | DELETE
 | DEFERRED
 | DISCARD