From aa82a038f1aa1739885592b57251eb77eaff9991 Mon Sep 17 00:00:00 2001
From: Alkaid Jiang <38248129+jyz0309@users.noreply.github.com>
Date: Tue, 9 Mar 2021 15:54:55 +0800
Subject: [PATCH] types: fix the bug about the wrong query result for decimal
 type  (#22507)

---
 executor/write_test.go | 13 +++++++++++++
 types/convert_test.go  |  9 +++++++++
 types/mydecimal.go     |  7 +++++++
 3 files changed, 29 insertions(+)

diff --git a/executor/write_test.go b/executor/write_test.go
index 9bcaa68199b4b..1721d726179b1 100644
--- a/executor/write_test.go
+++ b/executor/write_test.go
@@ -3901,6 +3901,19 @@ func (s *testSerialSuite) TestIssue20840(c *C) {
 	tk.MustExec("drop table t1")
 }
 
+func (s *testSerialSuite) TestIssue22496(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t12")
+	tk.MustExec("create table t12(d decimal(15,2));")
+	_, err := tk.Exec("insert into t12 values('1,9999.00')")
+	c.Assert(err, NotNil)
+	tk.MustExec("set sql_mode=''")
+	tk.MustExec("insert into t12 values('1,999.00');")
+	tk.MustQuery("SELECT * FROM t12;").Check(testkit.Rows("1.00"))
+	tk.MustExec("drop table t12")
+}
+
 func (s *testSuite) TestEqualDatumsAsBinary(c *C) {
 	tests := []struct {
 		a    []interface{}
diff --git a/types/convert_test.go b/types/convert_test.go
index 9c3326a7ae846..34a5f5aea5435 100644
--- a/types/convert_test.go
+++ b/types/convert_test.go
@@ -243,6 +243,15 @@ func (s *testTypeConvertSuite) TestConvertType(c *C) {
 	v, err = Convert("-10000", ft)
 	c.Assert(terror.ErrorEqual(err, ErrOverflow), IsTrue, Commentf("err %v", err))
 	c.Assert(v.(*MyDecimal).String(), Equals, "-9999.9999")
+	v, err = Convert("1,999.00", ft)
+	c.Assert(terror.ErrorEqual(err, ErrBadNumber), IsTrue, Commentf("err %v", err))
+	c.Assert(v.(*MyDecimal).String(), Equals, "1.0000")
+	v, err = Convert("1,999,999.00", ft)
+	c.Assert(terror.ErrorEqual(err, ErrBadNumber), IsTrue, Commentf("err %v", err))
+	c.Assert(v.(*MyDecimal).String(), Equals, "1.0000")
+	v, err = Convert("199.00 ", ft)
+	c.Assert(err, IsNil)
+	c.Assert(v.(*MyDecimal).String(), Equals, "199.0000")
 
 	// Test Datum.ToDecimal with bad number.
 	d := NewDatum("hello")
diff --git a/types/mydecimal.go b/types/mydecimal.go
index f86d74206049b..acd5ca48ff01d 100644
--- a/types/mydecimal.go
+++ b/types/mydecimal.go
@@ -389,6 +389,8 @@ func (d *MyDecimal) ToString() (str []byte) {
 
 // FromString parses decimal from string.
 func (d *MyDecimal) FromString(str []byte) error {
+	// strErr is used to check str is bad number or not
+	var strErr error
 	for i := 0; i < len(str); i++ {
 		if !isSpace(str[i]) {
 			str = str[i:]
@@ -419,6 +421,8 @@ func (d *MyDecimal) FromString(str []byte) error {
 			endIdx++
 		}
 		digitsFrac = endIdx - strIdx - 1
+	} else if strIdx < len(str) && (str[strIdx] != 'e' && str[strIdx] != 'E' && str[strIdx] != ' ') {
+		strErr = ErrBadNumber
 	} else {
 		digitsFrac = 0
 		endIdx = strIdx
@@ -519,6 +523,9 @@ func (d *MyDecimal) FromString(str []byte) error {
 		d.negative = false
 	}
 	d.resultFrac = d.digitsFrac
+	if strErr != nil {
+		return strErr
+	}
 	return err
 }