MDEV-24597 Explicit column name error in CTE of UNION

This bug manifested itself when executing queries with multiple reference
to a CTE specified by a query expression with union and having its
column names explicitly declared. In this case the server returned a bogus
error message about unknown column name. It happened because while for the
first reference to the CTE the names of the columns returned by the CTE
specification were properly changed to match the CTE definition for the
other references it was not done. This was a consequence  of not quite
complete code of the function With_element::clone_parsed_spec() that forgot
to set the reference to the CTE definition for unit structures representing
non-first CTE references.

Approved by dmitry.shulga@mariadb.com

mysql-test/r/cte_nonrecursive.result

@@ -618,7 +618,7 @@ with t(c) as (select a from t1 where b >= 'c')
 select * from t r1, t r2 where r1.c=r2.c and r2.c=4;
 show create view v4;
 View	Create View	character_set_client	collation_connection
-v4	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v4` AS with t as (select `test`.`t1`.`a` AS `c` from `test`.`t1` where `test`.`t1`.`b` >= 'c')select `r1`.`c` AS `c`,`r2`.`c` AS `d` from (`t` `r1` join (select `test`.`t1`.`a` AS `c` from `test`.`t1` where `test`.`t1`.`b` >= 'c') `r2`) where `r1`.`c` = `r2`.`c` and `r2`.`c` = 4	latin1	latin1_swedish_ci
+v4	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v4` AS with t as (select `test`.`t1`.`a` AS `c` from `test`.`t1` where `test`.`t1`.`b` >= 'c')select `r1`.`c` AS `c`,`r2`.`c` AS `d` from (`t` `r1` join `t` `r2`) where `r1`.`c` = `r2`.`c` and `r2`.`c` = 4	latin1	latin1_swedish_ci
 select * from v4;
 c	d
 4	4
@@ -1126,7 +1126,7 @@ NULL	UNION RESULT	<union2,5>	ALL	NULL	NULL	NULL	NULL	NULL	NULL
 NULL	UNION RESULT	<union9,12>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
 NULL	UNION RESULT	<union1,6>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
 Warnings:
-Note	1003	with cte_e as (with cte_o as (with cte_i as (select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 7)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 1)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 3 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1 union select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 4 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1)select `cte_e1`.`a` AS `a` from `cte_e` `cte_e1` where `cte_e1`.`a` > 1 union select `cte_e2`.`a` AS `a` from (with cte_o as (with cte_i as (select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 7)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 1)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 3 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 union select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 4 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7) `cte_e2`
+Note	1003	with cte_e as (with cte_o as (with cte_i as (select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 7)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 1)select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` < 3 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1 union select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` > 4 and `test`.`t1`.`a` > 1 and `test`.`t1`.`a` < 7 and `test`.`t1`.`a` > 1)select `cte_e1`.`a` AS `a` from `cte_e` `cte_e1` where `cte_e1`.`a` > 1 union select `cte_e2`.`a` AS `a` from `cte_e` `cte_e2`
 drop table t1;
 #
 # MDEV-13753: embedded CTE in a VIEW created in prepared statement
@@ -1725,4 +1725,42 @@ drop table db1.t1;
 drop database db1;
 create database test;
 use test;
+#
+# MDEV-24597: CTE with union used multiple times in query
+#
+with cte(a) as
+(select 1 as d union select 2 as d)
+select a from cte as r1
+union
+select a from cte as r2;
+a
+1
+2
+create table t1 (a int, b int) engine=myisam;
+insert into t1 values
+(3,30), (7,70), (1,10), (7,71), (2,20), (7,72), (3,33), (4,44),
+(5,50), (4,40), (3,33), (4,42), (4,43), (5,51);
+with cte(c) as
+(select a from t1 where b < 30 union select a from t1 where b > 40)
+select * from cte as r1, cte as r2 where r1.c = r2.c;
+c	c
+1	1
+2	2
+7	7
+4	4
+5	5
+with cte(a,c) as
+(
+select a, count(*) from t1 group by a having count(*) = 1
+union
+select a, count(*) from t1 group by a having count(*) = 3
+)
+select a, c from cte as r1 where a < 3
+union
+select a, c from cte as r2 where a > 4;
+a	c
+1	1
+2	1
+7	3
+drop table t1;
 # End of 10.2 tests

mysql-test/t/cte_nonrecursive.test

@@ -1230,4 +1230,35 @@ drop database db1;
 create database test;
 use test;
 
+--echo #
+--echo # MDEV-24597: CTE with union used multiple times in query
+--echo #
+
+with cte(a) as
+(select 1 as d union select 2 as d)
+select a from cte as r1
+union
+select a from cte as r2;
+
+create table t1 (a int, b int) engine=myisam;
+insert into t1 values
+(3,30), (7,70), (1,10), (7,71), (2,20), (7,72), (3,33), (4,44),
+(5,50), (4,40), (3,33), (4,42), (4,43), (5,51);
+
+with cte(c) as
+(select a from t1 where b < 30 union select a from t1 where b > 40)
+select * from cte as r1, cte as r2 where r1.c = r2.c;
+
+with cte(a,c) as
+(
+  select a, count(*) from t1 group by a having count(*) = 1
+  union
+  select a, count(*) from t1 group by a having count(*) = 3
+)
+select a, c from cte as r1 where a < 3
+union
+select a, c from cte as r2 where a > 4;
+
+drop table t1;
+
 --echo # End of 10.2 tests

sql/sql_cte.cc

@@ -879,6 +879,7 @@ st_select_lex_unit *With_element::clone_parsed_spec(THD *thd,
     with_table->next_global= spec_tables;
   }
   res= &lex->unit;
+  res->with_element= this;
 
   lex->unit.include_down(with_table->select_lex);
   lex->unit.set_slave(with_select);