From d251cedd8d20a3086bb593996bf3af4346e58f12 Mon Sep 17 00:00:00 2001
From: Galina Shalygina <galina.shalygina@mariadb.com>
Date: Tue, 13 Mar 2018 02:53:48 +0200
Subject: [PATCH] MDEV-15478: Lost name of a explicitly named CTE column used
 in             the non-recursive CTE defined with UNION

The problem appears as the columns of the non-recursive CTE weren't renamed.
The renaming procedure was called for recursive CTEs only.

To fix it in the procedure st_select_lex_unit::prepare
With_element::rename_columns_of_derived_unit is called now for both CTEs:
recursive and non-recursive.
---
 mysql-test/r/cte_nonrecursive.result | 37 ++++++++++++++++++++++++++++
 mysql-test/t/cte_nonrecursive.test   | 23 +++++++++++++++++
 sql/sql_union.cc                     |  2 +-
 3 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/cte_nonrecursive.result b/mysql-test/r/cte_nonrecursive.result
index f2bfce9f6ba..001df909bcf 100644
--- a/mysql-test/r/cte_nonrecursive.result
+++ b/mysql-test/r/cte_nonrecursive.result
@@ -1425,3 +1425,40 @@ a
 DEALLOCATE PREPARE stmt;
 DROP TABLE t1;
 DROP VIEW v1,v2;
+#
+# MDEV-15478: Lost name of a explicitly named CTE column used in
+#             the non-recursive CTE defined with UNION
+#
+CREATE TABLE t1 (x int, y int);
+INSERT INTO t1 VALUES (1,2),(2,7),(3,3);
+WITH cte(a) AS (SELECT 1 UNION SELECT 2) SELECT * FROM cte;
+a
+1
+2
+WITH cte(a) AS (SELECT 1 UNION SELECT 2) SELECT a FROM cte;
+a
+1
+2
+WITH cte(a) AS (SELECT 1 UNION ALL SELECT 1) SELECT a FROM cte;
+a
+1
+1
+WITH cte(a) AS (SELECT x from t1 UNION SELECT 4) SELECT a FROM cte;
+a
+1
+2
+3
+4
+WITH cte(a) AS (SELECT 4 UNION SELECT x FROM t1 UNION SELECT 5)
+SELECT a FROM cte;
+a
+4
+1
+2
+3
+5
+WITH cte(a,b) AS (SELECT 4,5 UNION SELECT 4,3) SELECT a,b FROM cte;
+a	b
+4	5
+4	3
+DROP TABLE t1;
diff --git a/mysql-test/t/cte_nonrecursive.test b/mysql-test/t/cte_nonrecursive.test
index 3d073183877..5e1770496f6 100644
--- a/mysql-test/t/cte_nonrecursive.test
+++ b/mysql-test/t/cte_nonrecursive.test
@@ -989,3 +989,26 @@ DEALLOCATE PREPARE stmt;
 
 DROP TABLE t1;
 DROP VIEW v1,v2;
+
+--echo #
+--echo # MDEV-15478: Lost name of a explicitly named CTE column used in
+--echo #             the non-recursive CTE defined with UNION
+--echo #
+
+CREATE TABLE t1 (x int, y int);
+INSERT INTO t1 VALUES (1,2),(2,7),(3,3);
+
+WITH cte(a) AS (SELECT 1 UNION SELECT 2) SELECT * FROM cte;
+
+WITH cte(a) AS (SELECT 1 UNION SELECT 2) SELECT a FROM cte;
+
+WITH cte(a) AS (SELECT 1 UNION ALL SELECT 1) SELECT a FROM cte;
+
+WITH cte(a) AS (SELECT x from t1 UNION SELECT 4) SELECT a FROM cte;
+
+WITH cte(a) AS (SELECT 4 UNION SELECT x FROM t1 UNION SELECT 5)
+SELECT a FROM cte;
+
+WITH cte(a,b) AS (SELECT 4,5 UNION SELECT 4,3) SELECT a,b FROM cte;
+
+DROP TABLE t1;
diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 524f6eb9c8d..19c9330481f 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -598,7 +598,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       types= first_sl->item_list;
     else if (sl == first_sl)
     {
-      if (is_recursive)
+      if (with_element)
       {
         if (derived->with->rename_columns_of_derived_unit(thd, this))
 	  goto err;