add test

expression/integration_test.go

@@ -10669,3 +10669,15 @@ func (s *testIntegrationSuite) TestIssue30101(c *C) {
 	tk.MustExec("insert into t1 values(9223372036854775808, 9223372036854775809);")
 	tk.MustQuery("select greatest(c1, c2) from t1;").Sort().Check(testkit.Rows("9223372036854775809"))
 }
+
+func (s *testIntegrationSuite) TestIssue30326(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(a int);")
+	tk.MustExec("insert into t values(1),(1),(2),(2);")
+	tk.MustExec("set tidb_window_concurrency = 1;")
+	err := tk.QueryToErr("select (FIRST_VALUE(1) over (partition by v.a)) as c3 from (select a from t where t.a = (select a from t t2 where t.a = t2.a)) as v;")
+	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "[executor:1242]Subquery returns more than 1 row")
+}