support of subselect without FROM reducing (SCRUM)

fixed bug of calling setup_fields without correct lex->current_select pointer in mysql_derived
more correct creation of reference in Item_field::fix_field


mysql-test/r/subselect.result:
  new explain with subselect reduced
mysql-test/t/subselect.test:
  new explain with subselect reduced
sql/item.cc:
  support of subselect without FROM reducing
  more correct creation of reference in Item_field::fix_field
sql/item.h:
  support of subselect without FROM reducing
sql/item_cmpfunc.cc:
  support of subselect without FROM reducing
sql/item_cmpfunc.h:
  support of subselect without FROM reducing
sql/item_func.cc:
  support of subselect without FROM reducing
sql/item_func.h:
  support of subselect without FROM reducing
sql/item_row.cc:
  support of subselect without FROM reducing
sql/item_row.h:
  support of subselect without FROM reducing
sql/item_strfunc.h:
  fixed layout
  support of subselect without FROM reducing
sql/item_subselect.cc:
  support of subselect without FROM reducing
sql/item_subselect.h:
  support of subselect without FROM reducing
sql/mysql_priv.h:
  reference in Item_field::fix_field related changes
sql/sql_base.cc:
  reference in Item_field::fix_field related changes
sql/sql_derived.cc:
  fixed bug of calling setup_fields without correct lex->current_select pointer

2 files changed, 38 insertions, 1 deletions

diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index 502fe0fad60..23aad50c6ae 100644
--- a/mysql-test/r/subselect.result
+++ b/mysql-test/r/subselect.result
@@ -1,13 +1,32 @@
 select (select 2);
 (select 2)
 2
+explain select (select 2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
 SELECT (SELECT 1) UNION SELECT (SELECT 2);
 (SELECT 1)
 1
 2
+explain SELECT (SELECT 1) UNION SELECT (SELECT 2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
+Note	1247	Select 4 was reduced during optimisation
 SELECT (SELECT (SELECT 0 UNION SELECT 0));
 (SELECT (SELECT 0 UNION SELECT 0))
 0
+explain SELECT (SELECT (SELECT 0 UNION SELECT 0));
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+4	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING a=1) as a;
 Reference 'a' not supported (forward reference in item list)
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING b=1) as a,(SELECT 1 FROM (SELECT 1) as c HAVING a=1) as b;
@@ -20,8 +39,9 @@ Reference 'a' not supported (forward reference in item list)
 EXPLAIN SELECT 1 FROM (SELECT 1 as a) as b  HAVING (SELECT a)=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
-3	DEPENDENT SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+Warnings:
+Note	1247	Select 3 was reduced during optimisation
 SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
 1
 1
@@ -629,6 +649,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t	ref	id	id	5	const	1	Using where; Using index
 3	SUBSELECT	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
 Warnings:
+Note	1247	Select 3 was reduced during optimisation
 Note	1247	Select 2 was reduced during optimisation
 EXPLAIN SELECT * FROM t WHERE id IN (SELECT 1 UNION SELECT 3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -752,6 +773,16 @@ NULL
 select 10.5 > ANY (SELECT * from t);
 10.5 > ANY (SELECT * from t)
 1
+explain select (select a+1) from t;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	ALL	NULL	NULL	NULL	NULL	3	
+Warnings:
+Note	1247	Select 2 was reduced during optimisation
+select (select a+1) from t;
+(select a+1)
+2.5
+NULL
+4.5
 drop table t;
 create table t (a float);
 select 10.5 IN (SELECT * from t LIMIT 1);
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index c77fc33f0ea..4e8e71e50f8 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -1,6 +1,9 @@
 select (select 2);
+explain select (select 2);
 SELECT (SELECT 1) UNION SELECT (SELECT 2);
+explain SELECT (SELECT 1) UNION SELECT (SELECT 2);
 SELECT (SELECT (SELECT 0 UNION SELECT 0));
+explain SELECT (SELECT (SELECT 0 UNION SELECT 0));
 -- error 1245
 SELECT (SELECT 1 FROM (SELECT 1) as b HAVING a=1) as a;
 -- error 1245
@@ -424,6 +427,8 @@ select 1.5 > ALL (SELECT * from t);
 select 10.5 > ALL (SELECT * from t);
 select 1.5 > ANY (SELECT * from t);
 select 10.5 > ANY (SELECT * from t);
+explain select (select a+1) from t;
+select (select a+1) from t;
 drop table t;
 
 #LIMIT is not supported now
@@ -433,6 +438,7 @@ select 10.5 IN (SELECT * from t LIMIT 1);
 -- error 1235
 select 10.5 IN (SELECT * from t LIMIT 1 UNION SELECT 1.5);
 drop table t;
+
 create table t1 (a int, b int, c varchar(10));
 create table t2 (a int);
 insert into t1 values (1,2,'a'),(2,3,'b'),(3,4,'c');