explaintest: use a separate database for each case

cmd/explaintest/r/black_list.result

@@ -1,18 +1,17 @@
 set tidb_cost_model_version=1;
-use test;
 drop table if exists t;
 create table t (a int);
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
 TableReader	3323.33	root		data:Selection
-└─Selection	3323.33	cop[tikv]		lt(test.t.a, 1)
+└─Selection	3323.33	cop[tikv]		lt(black_list.t.a, 1)
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 insert into mysql.opt_rule_blacklist values('predicate_push_down');
 admin reload opt_rule_blacklist;
 
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
-Selection	8000.00	root		lt(test.t.a, 1)
+Selection	8000.00	root		lt(black_list.t.a, 1)
 └─TableReader	10000.00	root		data:TableFullScan
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 delete from mysql.opt_rule_blacklist where name='predicate_push_down';
@@ -21,14 +20,14 @@ admin reload opt_rule_blacklist;
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
 TableReader	3323.33	root		data:Selection
-└─Selection	3323.33	cop[tikv]		lt(test.t.a, 1)
+└─Selection	3323.33	cop[tikv]		lt(black_list.t.a, 1)
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 insert into mysql.expr_pushdown_blacklist values('<', 'tikv,tiflash,tidb', 'for test');
 admin reload expr_pushdown_blacklist;
 
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
-Selection	8000.00	root		lt(test.t.a, 1)
+Selection	8000.00	root		lt(black_list.t.a, 1)
 └─TableReader	10000.00	root		data:TableFullScan
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 delete from mysql.expr_pushdown_blacklist where name='<' and store_type = 'tikv,tiflash,tidb' and reason = 'for test';
@@ -37,14 +36,14 @@ admin reload expr_pushdown_blacklist;
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
 TableReader	3323.33	root		data:Selection
-└─Selection	3323.33	cop[tikv]		lt(test.t.a, 1)
+└─Selection	3323.33	cop[tikv]		lt(black_list.t.a, 1)
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 insert into mysql.expr_pushdown_blacklist values('lt', 'tikv,tiflash,tidb', 'for test');
 admin reload expr_pushdown_blacklist;
 
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
-Selection	8000.00	root		lt(test.t.a, 1)
+Selection	8000.00	root		lt(black_list.t.a, 1)
 └─TableReader	10000.00	root		data:TableFullScan
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 delete from mysql.expr_pushdown_blacklist where name='lt' and store_type = 'tikv,tiflash,tidb' and reason = 'for test';
@@ -53,5 +52,5 @@ admin reload expr_pushdown_blacklist;
 explain format = 'brief' select * from t where a < 1;
 id	estRows	task	access object	operator info
 TableReader	3323.33	root		data:Selection
-└─Selection	3323.33	cop[tikv]		lt(test.t.a, 1)
+└─Selection	3323.33	cop[tikv]		lt(black_list.t.a, 1)
   └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo

cmd/explaintest/r/collation_agg_func_disabled.result

@@ -298,5 +298,3 @@ StreamAgg	1.00	root		funcs:max(Column#8)->Column#6
 select max(d collate utf8mb4_bin) from tt;
 max(d collate utf8mb4_bin)
 {"c": "c"}
-drop database collation_agg_func;
-use test

cmd/explaintest/r/collation_agg_func_enabled.result

@@ -295,5 +295,3 @@ StreamAgg	1.00	root		funcs:max(Column#8)->Column#6
 select max(d collate utf8mb4_bin) from tt;
 max(d collate utf8mb4_bin)
 {"c": "c"}
-drop database collation_agg_func;
-use test

cmd/explaintest/r/collation_check_use_collation_disabled.result

@@ -176,4 +176,3 @@ Projection	80000000.00	root		is_ipv4(cast(collation_check_use_collation.t0.c1, v
   │   └─TableFullScan	10000.00	cop[tikv]	table:t0	keep order:false, stats:pseudo
   └─TableReader(Probe)	10000.00	root		data:TableFullScan
     └─TableFullScan	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo
-use test

cmd/explaintest/r/collation_check_use_collation_enabled.result

@@ -195,4 +195,3 @@ Projection	80000000.00	root		is_ipv4(cast(collation_check_use_collation.t0.c1, v
   │   └─TableFullScan	10000.00	cop[tikv]	table:t0	keep order:false, stats:pseudo
   └─TableReader(Probe)	10000.00	root		data:TableFullScan
     └─TableFullScan	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo
-use test

cmd/explaintest/r/collation_misc_disabled.result

@@ -118,4 +118,3 @@ binary	binary	63	Yes	Yes	1
 ascii_bin	ascii	65	Yes	Yes	1
 utf8_bin	utf8	83	Yes	Yes	1
 gbk_bin	gbk	87	Yes	Yes	1
-use test;

cmd/explaintest/r/collation_misc_enabled.result

@@ -135,4 +135,3 @@ utf8mb4_0900_bin	utf8mb4	309		Yes	1
 utf8mb4_bin	utf8mb4	46	Yes	Yes	1
 utf8mb4_general_ci	utf8mb4	45		Yes	1
 utf8mb4_unicode_ci	utf8mb4	224		Yes	1
-use test;