Fix for LP#612894 Some aggregate functions (such as MIN MAX) work incorrectly in subqueries after getting NULL value

mysql-test/r/group_by.result:
  Added test that showed problems that no_rows_in_results() didn't work for expressions
mysql-test/r/subselect4.result:
  Test case for LP#612894
mysql-test/t/group_by.test:
  Added test that showed problems that no_rows_in_results() didn't work for expressions
mysql-test/t/subselect4.test:
  Test case for LP#612894
sql/item.h:
  Added restore_to_before_no_rows_in_result()
  Added function processor for no_rows_in_results() and restore_to_before_no_rows_in_results() to ensure it works with functions
  Fix that above functions are handled by Item_ref()
sql/item_func.h:
  Ensure that no_rows_in_results() and restore_to_before_no_rows_in_result() are called for all function arguments
sql/item_sum.cc:
  Added restore_to_before_no_rows_in_result() to restore settings after Item_sum_hybrid::no_rows_in_result() was called.
  This is needed to handle the case where we have made 'make_const()' on the item in opt_sum(), but the item will be reused again in a sub query.
  Ignore multiple calls to no_rows_in_result() as Item_ref is calling it twice.
sql/item_sum.h:
  Added restore_to_before_no_rows_in_result();
sql/sql_select.cc:
  Added reset of no_rows_in_result() for JOIN::reinit()
sql/sql_select.h:
  Added marker if no_rows_in_result() is called.

1 files changed, 17 insertions, 0 deletions

diff --git a/mysql-test/t/group_by.test b/mysql-test/t/group_by.test
index c5b27ee1a62..c640a58d597 100644
--- a/mysql-test/t/group_by.test
+++ b/mysql-test/t/group_by.test
@@ -1219,6 +1219,23 @@ EXPLAIN SELECT MAX(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 SELECT MAX(t2.a) FROM t2 LEFT JOIN t1 ON t2.a = t1.a;
 DROP TABLE t1, t2;
 
+#
+# min() returns wrong value when used in expression when there is no matching
+# rows
+#
+
+CREATE TABLE t1 (a int(11) NOT NULL);
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (
+ key_col int(11) NOT NULL,
+ KEY (key_col)
+);
+INSERT INTO t2 VALUES (1),(2);
+
+select min(t2.key_col) from t1,t2 where t1.a=1;
+select min(t2.key_col) from t1,t2 where t1.a > 1000;
+select min(t2.key_col)+1 from t1,t2 where t1.a> 1000;
+drop table t1,t2;
 
 --echo #