Fix for LP bug#993726

Optimization of aggregate functions detected constant under max() and evalueted it, but condition in the WHWRE clause (which is always FALSE) was not taken into account

mysql-test/r/group_by.result

@@ -2059,4 +2059,16 @@ MIN(a)	b
 0	a
 
 DROP TABLE t1;
+#
+# LP bug#993726 Wrong result from a query with ALL subquery predicate in WHERE
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (0);
+SELECT 1 FROM t1 WHERE 1 > ALL(SELECT 1 FROM t1 WHERE a!=0);
+1
+1
+SELECT max(1) FROM t1 WHERE a!=0;
+max(1)
+NULL
+drop table t1;
 # End of 5.2 tests

mysql-test/t/group_by.test

@@ -1425,4 +1425,13 @@ let $query= SELECT MIN(a), b FROM t1 WHERE t1.b = 'a' GROUP BY b;
 --echo
 DROP TABLE t1;
 
+--echo #
+--echo # LP bug#993726 Wrong result from a query with ALL subquery predicate in WHERE
+--echo #
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (0);
+SELECT 1 FROM t1 WHERE 1 > ALL(SELECT 1 FROM t1 WHERE a!=0);
+SELECT max(1) FROM t1 WHERE a!=0;
+drop table t1;
+
 --echo # End of 5.2 tests

sql/opt_sum.cc

@@ -403,7 +403,7 @@ int opt_sum_query(THD *thd,
 	  }
           removed_tables|= table->map;
         }
-        else if (!expr->const_item() || !is_exact_count)
+        else if (!expr->const_item() || !is_exact_count || conds)
         {
           /*
             The optimization is not applicable in both cases:
@@ -413,6 +413,8 @@ int opt_sum_query(THD *thd,
             NULL if the query does not return any rows. Thus, if we are not
             able to determine if the query returns any rows, we can't apply
             the optimization and replace MIN/MAX with a constant.
+            (c) there is a WHERE clause. The WHERE conditions may result in
+            an empty result, but the clause cannot be taken into account here.
           */
           const_result= 0;
           break;