types: fix the bug about the wrong query result for decimal type

executor/write_test.go

@@ -3868,6 +3868,17 @@ 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("set sql_mode=''")
+ tk.MustExec("create table t12(d decimal(15,2));")
+ tk.MustExec("insert into t12 values('1,999.00');")
+ tk.MustQuery("SELECT * FROM t12;").Check(testkit.Rows("0.00"))
+ tk.MustExec("drop table t12")
+}
+
 func (s *testSuite) TestEqualDatumsAsBinary(c *C) {
  tests := []struct {
  a []interface{}

types/convert_test.go

@@ -243,6 +243,12 @@ 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, "0.0000")
+ 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, "0.0000")
 
  // Test Datum.ToDecimal with bad number.
  d := NewDatum("hello")

types/mydecimal.go

@@ -419,6 +419,9 @@ func (d *MyDecimal) FromString(str []byte) error {
  endIdx++
  }
  digitsFrac = endIdx - strIdx - 1
+ } else if strIdx < len(str) && (str[strIdx] != 'e' && str[strIdx] != 'E') {
+ *d = zeroMyDecimal
+ return ErrBadNumber
  } else {
  digitsFrac = 0
  endIdx = strIdx