Fixed bug #29392.

This bug may manifest itself for select queries over a multi-table view
that includes an ORDER BY clause in its definition. If the select list of 
the query contains references to the same view column with different
aliases the names of the columns in the result output will be nevertheless
the same, coinciding with one of the alias.

The bug happened because the method Item_ref::get_tmp_table_item that
was inherited by the class Item_direct_view_ref ignored the fact that
the name of the view column reference must be inherited by the fields
of the temporary table that was created in order to get the result rows
sorted.


mysql-test/r/view.result:
  Added a test case for bug #29392.
mysql-test/t/view.test:
  Added a test case for bug #29392.
sql/item.h:
  Fixed bug #29392.
  This bug may manifest itself for select queries over a multi-table view
  that includes an ORDER BY clause in its definition. If the select list of 
  the query contains references to the same view column with different
  aliases the names of the columns in the result output will be nevertheless
  the same, coinciding with one of the alias.
  
  The bug happened because the method Item_ref::get_tmp_table_item that
  was inherited by the class Item_direct_view_ref ignored the fact that
  the name of the view column reference must be inherited by the fields
  of the temporary table that was created in order to get the result rows
  sorted.
  
  Fixed by providing a proper implementation of the get_tmp_table_item 
  method for the Item_direct_view_ref class.

mysql-test/r/view.result

@@ -3500,4 +3500,51 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
 DROP VIEW v1;
 DROP TABLE t1;
+CREATE TABLE t1 (
+person_id int NOT NULL PRIMARY KEY,
+username varchar(40) default NULL,
+status_flg char(1) NOT NULL default 'A'
+);
+CREATE TABLE t2 (
+person_role_id int NOT NULL auto_increment PRIMARY KEY,
+role_id int NOT NULL,
+person_id int NOT NULL,
+INDEX idx_person_id (person_id),
+INDEX idx_role_id (role_id)
+);
+CREATE TABLE t3 (
+role_id int NOT NULL auto_increment PRIMARY KEY,
+role_name varchar(100) default NULL,
+app_name varchar(40) NOT NULL,
+INDEX idx_app_name(app_name)
+);
+CREATE VIEW v1 AS 
+SELECT profile.person_id AS person_id
+FROM t1 profile, t2 userrole, t3 role
+WHERE userrole.person_id = profile.person_id AND
+role.role_id = userrole.role_id AND
+profile.status_flg = 'A'
+  ORDER BY profile.person_id,role.app_name,role.role_name;
+INSERT INTO  t1 VALUES
+(6,'Sw','A'), (-1136332546,'ols','e'), (0,'    *\n','0'),
+(-717462680,'ENTS Ta','0'), (-904346964,'ndard SQL\n','0');
+INSERT INTO t2 VALUES
+(1,3,6),(2,4,7),(3,5,8),(4,6,9),(5,1,6),(6,1,7),(7,1,8),(8,1,9),(9,1,10);
+INSERT INTO t3 VALUES 
+(1,'NUCANS_APP_USER','NUCANSAPP'),(2,'NUCANS_TRGAPP_USER','NUCANSAPP'),
+(3,'IA_INTAKE_COORDINATOR','IACANS'),(4,'IA_SCREENER','IACANS'),
+(5,'IA_SUPERVISOR','IACANS'),(6,'IA_READONLY','IACANS'),
+(7,'SOC_USER','SOCCANS'),(8,'CAYIT_USER','CAYITCANS'),
+(9,'RTOS_DCFSPOS_SUPERVISOR','RTOS');
+EXPLAIN SELECT t.person_id AS a, t.person_id AS b FROM v1 t WHERE t.person_id=6;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	profile	const	PRIMARY	PRIMARY	4	const	1	Using temporary; Using filesort
+1	SIMPLE	userrole	ref	idx_person_id,idx_role_id	idx_person_id	4	const	2	
+1	SIMPLE	role	eq_ref	PRIMARY	PRIMARY	4	test.userrole.role_id	1	
+SELECT t.person_id AS a, t.person_id AS b FROM v1 t WHERE t.person_id=6;
+a	b
+6	6
+6	6
+DROP VIEW v1;
+DROP TABLE t1,t2,t3;
 End of 5.0 tests.

mysql-test/t/view.test

@@ -3348,4 +3348,59 @@ EXPLAIN SELECT a, SUM(b) FROM v1 WHERE a=1 GROUP BY a;
 DROP VIEW v1;
 DROP TABLE t1;
 
+#
+# Bug #29392: SELECT over a multi-table view with ORDER BY  
+#             selecting the same view column with two different aliases  
+#
+
+CREATE TABLE t1 (
+  person_id int NOT NULL PRIMARY KEY,
+  username varchar(40) default NULL,
+  status_flg char(1) NOT NULL default 'A'
+);
+
+CREATE TABLE t2 (
+  person_role_id int NOT NULL auto_increment PRIMARY KEY,
+  role_id int NOT NULL,
+  person_id int NOT NULL,
+  INDEX idx_person_id (person_id),
+  INDEX idx_role_id (role_id)
+);
+
+CREATE TABLE t3 (
+  role_id int NOT NULL auto_increment PRIMARY KEY,
+  role_name varchar(100) default NULL,
+  app_name varchar(40) NOT NULL,
+  INDEX idx_app_name(app_name)
+);
+
+CREATE VIEW v1 AS 
+SELECT profile.person_id AS person_id
+  FROM t1 profile, t2 userrole, t3 role
+    WHERE userrole.person_id = profile.person_id AND
+          role.role_id = userrole.role_id AND
+          profile.status_flg = 'A'
+  ORDER BY profile.person_id,role.app_name,role.role_name;
+
+INSERT INTO  t1 VALUES
+ (6,'Sw','A'), (-1136332546,'ols','e'), (0,'    *\n','0'),
+ (-717462680,'ENTS Ta','0'), (-904346964,'ndard SQL\n','0');
+
+INSERT INTO t2 VALUES
+  (1,3,6),(2,4,7),(3,5,8),(4,6,9),(5,1,6),(6,1,7),(7,1,8),(8,1,9),(9,1,10);
+
+INSERT INTO t3 VALUES 
+  (1,'NUCANS_APP_USER','NUCANSAPP'),(2,'NUCANS_TRGAPP_USER','NUCANSAPP'),
+  (3,'IA_INTAKE_COORDINATOR','IACANS'),(4,'IA_SCREENER','IACANS'),
+  (5,'IA_SUPERVISOR','IACANS'),(6,'IA_READONLY','IACANS'),
+  (7,'SOC_USER','SOCCANS'),(8,'CAYIT_USER','CAYITCANS'),
+  (9,'RTOS_DCFSPOS_SUPERVISOR','RTOS');
+ 
+EXPLAIN SELECT t.person_id AS a, t.person_id AS b FROM v1 t WHERE t.person_id=6;
+SELECT t.person_id AS a, t.person_id AS b FROM v1 t WHERE t.person_id=6;
+
+DROP VIEW v1;
+DROP TABLE t1,t2,t3;
+
 --echo End of 5.0 tests.
+

sql/item.h

@@ -1983,6 +1983,12 @@ public:
 
   bool fix_fields(THD *, Item **);
   bool eq(const Item *item, bool binary_cmp) const;
+  Item *get_tmp_table_item(THD *thd)
+  {
+    Item *item= Item_ref::get_tmp_table_item(thd);
+    item->name= name;
+    return item;
+  }
   virtual Ref_Type ref_type() { return VIEW_REF; }
 };