From e80bab6d46869a77d56bdaef29d950bcbd4fdc40 Mon Sep 17 00:00:00 2001
From: Lonng <heng@lonng.org>
Date: Tue, 15 Oct 2019 17:51:25 +0800
Subject: [PATCH] fix the STR_TO_DATE incompatible between MySQL and TiDB
 (#12623)

Signed-off-by: Lonng <heng@lonng.org>
---
 executor/executor_test.go  |  3 +++
 expression/builtin_time.go |  1 +
 types/time.go              | 18 ++++++++----------
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/executor/executor_test.go b/executor/executor_test.go
index 5a1ab52dc2..f999c5cef7 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -3997,6 +3997,9 @@ func (s *testSuite4) TearDownTest(c *C) {
 
 func (s *testSuiteP1) TestStrToDateBuiltin(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
+	tk.MustQuery(`select str_to_date('20190101','%Y%m%d%!') from dual`).Check(testkit.Rows("2019-01-01"))
+	tk.MustQuery(`select str_to_date('20190101','%Y%m%d%f') from dual`).Check(testkit.Rows("2019-01-01 00:00:00.000000"))
+	tk.MustQuery(`select str_to_date('20190101','%Y%m%d%H%i%s') from dual`).Check(testkit.Rows("2019-01-01 00:00:00"))
 	tk.MustQuery(`select str_to_date('18/10/22','%y/%m/%d') from dual`).Check(testkit.Rows("2018-10-22"))
 	tk.MustQuery(`select str_to_date('a18/10/22','%y/%m/%d') from dual`).Check(testkit.Rows("<nil>"))
 	tk.MustQuery(`select str_to_date('69/10/22','%y/%m/%d') from dual`).Check(testkit.Rows("2069-10-22"))
diff --git a/expression/builtin_time.go b/expression/builtin_time.go
index f121613370..8d29ec263e 100644
--- a/expression/builtin_time.go
+++ b/expression/builtin_time.go
@@ -1788,6 +1788,7 @@ func (c *strToDateFunctionClass) getRetTp(ctx sessionctx.Context, arg Expression
 	if err != nil || isNull {
 		return
 	}
+
 	isDuration, isDate := types.GetFormatType(format)
 	if isDuration && !isDate {
 		tp = mysql.TypeDuration
diff --git a/types/time.go b/types/time.go
index 746e0507fb..739db5fd2c 100644
--- a/types/time.go
+++ b/types/time.go
@@ -2199,6 +2199,11 @@ func strToDate(t *MysqlTime, date string, format string, ctx map[string]int) boo
 		return true
 	}
 
+	if len(date) == 0 {
+		ctx[token] = 0
+		return true
+	}
+
 	dateRemain, succ := matchDateWithToken(t, date, token, ctx)
 	if !succ {
 		return false
@@ -2316,21 +2321,14 @@ func GetFormatType(format string) (isDuration, isDate bool) {
 			isDuration, isDate = false, false
 			break
 		}
-		var durationTokens bool
-		var dateTokens bool
 		if len(token) >= 2 && token[0] == '%' {
 			switch token[1] {
-			case 'h', 'H', 'i', 'I', 's', 'S', 'k', 'l':
-				durationTokens = true
+			case 'h', 'H', 'i', 'I', 's', 'S', 'k', 'l', 'f':
+				isDuration = true
 			case 'y', 'Y', 'm', 'M', 'c', 'b', 'D', 'd', 'e':
-				dateTokens = true
+				isDate = true
 			}
 		}
-		if durationTokens {
-			isDuration = true
-		} else if dateTokens {
-			isDate = true
-		}
 		if isDuration && isDate {
 			break
 		}