From 114e18b8b68a00b3829ac231cc8f84187f529287 Mon Sep 17 00:00:00 2001
From: Igor Babaev <igor@askmonty.org>
Date: Sat, 20 Nov 2021 21:35:54 -0800
Subject: [PATCH] MDEV-26470 "No database" selected when using CTE in a
 subquery of DELETE statement

This bug led to reporting bogus messages "No database selected" for DELETE
statements if they used subqueries in their WHERE conditions and these
subqueries contained references to CTEs.
The bug happened because the grammar rule for DELETE statement did not
call the function LEX::check_cte_dependencies_and_resolve_references() and
as a result of it references to CTEs were not identified as such.

Approved by Oleksandr Byelkin <sanja@mariadb.com>
---
 mysql-test/r/cte_nonrecursive.result | 22 ++++++++++++++++++++++
 mysql-test/t/cte_nonrecursive.test   | 23 +++++++++++++++++++++++
 sql/sql_yacc.yy                      |  4 ++++
 3 files changed, 49 insertions(+)

diff --git a/mysql-test/r/cte_nonrecursive.result b/mysql-test/r/cte_nonrecursive.result
index d9b7f054271..b2fee0d3c6f 100644
--- a/mysql-test/r/cte_nonrecursive.result
+++ b/mysql-test/r/cte_nonrecursive.result
@@ -2162,4 +2162,26 @@ a
 1
 3
 drop table t1,t2;
+#
+# MDEV-26470: CTE in WITH clause of subquery used in DELETE
+#
+create table t1 (a int);
+insert into t1 values (3), (7), (1), (5);
+create table t2 (b int);
+insert into t2 values (4), (1), (3), (2);
+delete from t1
+where a in (with cte(a) as (select * from t2 where b <=2) select a from cte);
+select * from t1;
+a
+3
+7
+5
+insert into t1 values (1), (3);
+delete t1 from t1, t2
+where t1.a=t2.b or
+t1.a in (with cte(a) as (select b+1 from t2) select * from cte);
+select * from t1;
+a
+7
+drop table t1,t2;
 # End of 10.2 tests
diff --git a/mysql-test/t/cte_nonrecursive.test b/mysql-test/t/cte_nonrecursive.test
index 4618e024d2b..175be8b9881 100644
--- a/mysql-test/t/cte_nonrecursive.test
+++ b/mysql-test/t/cte_nonrecursive.test
@@ -1601,4 +1601,27 @@ select * from t2;
 
 drop table t1,t2;
 
+--echo #
+--echo # MDEV-26470: CTE in WITH clause of subquery used in DELETE
+--echo #
+
+create table t1 (a int);
+insert into t1 values (3), (7), (1), (5);
+
+create table t2 (b int);
+insert into t2 values (4), (1), (3), (2);
+
+delete from t1
+  where a in (with cte(a) as (select * from t2 where b <=2) select a from cte);
+select * from t1;
+
+insert into t1 values (1), (3);
+
+delete t1 from t1, t2
+  where t1.a=t2.b or
+        t1.a in (with cte(a) as (select b+1 from t2) select * from cte);
+select * from t1;
+
+drop table t1,t2;
+
 --echo # End of 10.2 tests
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 4dd292258d3..a4b105862f3 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -12668,6 +12668,10 @@ delete:
             lex->select_lex.init_order();
           }
           opt_delete_options single_multi
+          {
+            if (Lex->check_cte_dependencies_and_resolve_references())
+              MYSQL_YYABORT;
+          }
         ;
 
 single_multi: