expression: fix ADD_DATE daylight saving time change (pingcap#20871) (p…

…ingcap#20888)

executor/executor_test.go

@@ -6166,3 +6166,12 @@ func (s *testSuite) TestIssue20237(c *C) {
 	tk.MustExec(`insert into s values(-37),(105),(-22),(-56),(124),(105),(111),(-5);`)
 	tk.MustQuery(`select count(distinct t.a, t.b) from t join s on t.b= s.b;`).Check(testkit.Rows("4"))
 }
+
+func (s *testSuite) TestIssue19667(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 DATETIME)")
+	tk.MustExec("INSERT INTO t VALUES('1988-04-17 01:59:59')")
+	tk.MustQuery(`SELECT DATE_ADD(a, INTERVAL 1 SECOND) FROM t`).Check(testkit.Rows("1988-04-17 02:00:00"))
+}

expression/builtin_time.go

@@ -2852,7 +2852,7 @@ func (du *baseDateArithmitical) add(ctx sessionctx.Context, date types.Time, int
 		return types.ZeroTime, true, err
 	}
 
-	goTime, err := date.GoTime(time.Local)
+	goTime, err := date.GoTime(time.UTC)
 	if err := handleInvalidTimeError(ctx, err); err != nil {
 		return types.ZeroTime, true, err
 	}

types/core_time.go

@@ -251,7 +251,7 @@ func compareTime(a, b CoreTime) int {
 // When we execute select date_add('2018-01-31',interval 1 month) in mysql we got 2018-02-28
 // but in tidb we got 2018-03-03.
 // Dig it and we found it's caused by golang api time.Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time ,
-// it says October 32 converts to November 1 ,it conflits with mysql.
+// it says October 32 converts to November 1 ,it conflicts with mysql.
 // See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_date-add
 func AddDate(year, month, day int64, ot gotime.Time) (nt gotime.Time) {
 	df := getFixDays(int(year), int(month), int(day), ot)