Bug #28499924: INCORRECT BEHAVIOR WITH UNION IN SUBQUERY

test case

mysql-test/r/subselect2.result

@@ -394,3 +394,25 @@ select null in (select a from t1 where a < out3.a union select a from t2 where
 (select a from t3) +1 < out3.a+1) from t3 out3;
 ERROR 21000: Subquery returns more than 1 row
 drop table t1, t2, t3;
+CREATE TABLE t1(
+q11 int, q12 int, q13 int, q14 int, q15 int, q16 int, q17 int, q18 int, q19 int,
+q21 int, q22 int, q23 int, q24 int, q25 int, q26 int, q27 int, q28 int, q29 int,
+f1 int
+);
+CREATE TABLE t2(f2 int, f21 int, f3 timestamp, f4 int, f5 int, f6 int);
+INSERT INTO t1 (f1) VALUES (1),(1),(2),(2);
+INSERT INTO t2 VALUES (1,1,"2004-02-29 11:11:11",0,0,0), (2,2,"2004-02-29 11:11:11",0,0,0);
+SELECT f1,
+(SELECT t.f21 from t2 t where max(
+q11+q12+q13+q14+q15+q16+q17+q18+q19+
+q21+q22+q23+q24+q25+q26+q27+q28+q29) = t.f2 UNION
+SELECT t.f3 FROM t2 AS t WHERE t1.f1=t.f2 AND t.f3=MAX(t1.f1) UNION
+SELECT 1 LIMIT 1) AS test
+FROM t1 GROUP BY f1;
+f1	test
+1	1
+2	1
+Warnings:
+Warning	1292	Incorrect datetime value: '1'
+Warning	1292	Incorrect datetime value: '2'
+DROP TABLE t1,t2;

mysql-test/t/subselect2.test

@@ -411,3 +411,23 @@ insert into t3 select a from t1;
 select null in (select a from t1 where a < out3.a union select a from t2 where
   (select a from t3) +1 < out3.a+1) from t3 out3;
 drop table t1, t2, t3;
+
+#
+# Bug #28499924: INCORRECT BEHAVIOR WITH UNION IN SUBQUERY
+#
+CREATE TABLE t1(
+  q11 int, q12 int, q13 int, q14 int, q15 int, q16 int, q17 int, q18 int, q19 int,
+  q21 int, q22 int, q23 int, q24 int, q25 int, q26 int, q27 int, q28 int, q29 int,
+  f1 int
+);
+CREATE TABLE t2(f2 int, f21 int, f3 timestamp, f4 int, f5 int, f6 int);
+INSERT INTO t1 (f1) VALUES (1),(1),(2),(2);
+INSERT INTO t2 VALUES (1,1,"2004-02-29 11:11:11",0,0,0), (2,2,"2004-02-29 11:11:11",0,0,0);
+SELECT f1,
+     (SELECT t.f21 from t2 t where max(
+          q11+q12+q13+q14+q15+q16+q17+q18+q19+
+          q21+q22+q23+q24+q25+q26+q27+q28+q29) = t.f2 UNION
+      SELECT t.f3 FROM t2 AS t WHERE t1.f1=t.f2 AND t.f3=MAX(t1.f1) UNION
+      SELECT 1 LIMIT 1) AS test
+ FROM t1 GROUP BY f1;
+DROP TABLE t1,t2;