From ad88eabd35b34c557de1a4eede6c8fe9201dc01e Mon Sep 17 00:00:00 2001
From: unknown <evgen@moonbone.local>
Date: Tue, 11 Jul 2006 00:34:37 +0400
Subject: [PATCH] Fixed bug#16302: Quantified subquery without any tables gives
 wrong results

The ALL/ANY subqueries are the subject of MIN/MAX optimization. The matter
of this optimization is to embed MIN() or MAX() function into the subquery
in order to get only one row by which we can tell whether the expression
with ALL/ANY subquery is true or false.
But when it is applied to a subquery like 'select a_constant' the reported bug
occurs. As no tables are specified in the subquery the do_select() function
isn't called for the optimized subquery and thus no values have been added
to a MIN()/MAX() function and it returns NULL instead of a_constant.
This leads to a wrong query result.

For the subquery like 'select a_constant' there is no reason to apply
MIN/MAX optimization because the subquery anyway will return at most one row.
Thus the Item_maxmin_subselect class is more appropriate for handling such
subqueries.

The Item_in_subselect::single_value_transformer() function now checks
whether tables are specified for the subquery. If no then this subselect is
handled like a UNION using an Item_maxmin_subselect object.


mysql-test/t/subselect.test:
  Added test case for bug#16302: Quantified subquery without any tables gives wrong results
mysql-test/r/subselect.result:
  Added test case for bug#16302: Quantified subquery without any tables gives wrong results
sql/item_subselect.cc:
  Fixed bug#16302: Quantified subquery without any tables gives wrong results

  The Item_in_subselect::single_value_transformer() function now checks
  whether tables are specified for the subquery. If no then this subselect is
  handled like a UNION using an Item_maxmin_subselect object.
---
 mysql-test/r/subselect.result | 18 ++++++++++++++++++
 mysql-test/t/subselect.test   | 10 ++++++++++
 sql/item_subselect.cc         |  3 ++-
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index 7925715a8b7..108f5dd1973 100644
--- a/mysql-test/r/subselect.result
+++ b/mysql-test/r/subselect.result
@@ -2835,3 +2835,21 @@ a
 4
 DROP TABLE t1,t2,t3;
 purge master logs before (select adddate(current_timestamp(), interval -4 day));
+select 1 from dual where 1 < any (select 2);
+1
+1
+select 1 from dual where 1 < all (select 2);
+1
+1
+select 1 from dual where 2 > any (select 1);
+1
+1
+select 1 from dual where 2 > all (select 1);
+1
+1
+select 1 from dual where 1 < any (select 2 from dual);
+1
+1
+select 1 from dual where 1 < all (select 2 from dual where 1!=1);
+1
+1
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index cbc7a3afb5f..f7d5e7f8713 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -1820,4 +1820,14 @@ DROP TABLE t1,t2,t3;
 
 purge master logs before (select adddate(current_timestamp(), interval -4 day));
 
+
+#
+# Bug#16302: Quantified subquery without any tables gives wrong results
+#
+select 1 from dual where 1 < any (select 2);
+select 1 from dual where 1 < all (select 2);
+select 1 from dual where 2 > any (select 1);
+select 1 from dual where 2 > all (select 1);
+select 1 from dual where 1 < any (select 2 from dual);
+select 1 from dual where 1 < all (select 2 from dual where 1!=1);
 # End of 4.1 tests
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 8241a8e0402..f6f8eec9af5 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -705,7 +705,8 @@ Item_in_subselect::single_value_transformer(JOIN *join,
     if (!select_lex->group_list.elements &&
         !select_lex->having &&
 	!select_lex->with_sum_func &&
-	!(select_lex->next_select()))
+	!(select_lex->next_select()) &&
+        select_lex->table_list.elements)
     {
       Item_sum_hybrid *item;
       if (func->l_op())