Builtin: add builtin function 'TO_DAYS'

expression/builtin_time.go

@@ -2051,7 +2051,24 @@ type builtinToDaysSig struct {
 
 // See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_to-days
 func (b *builtinToDaysSig) eval(row []types.Datum) (d types.Datum, err error) {
-	return d, errFunctionNotExists.GenByArgs("to_days")
+	args, err := b.evalArgs(row)
+	if err != nil {
+		return d, errors.Trace(err)
+	}
+	if args[0].IsNull() {
+		return d, nil
+	}
+	sc := b.ctx.GetSessionVars().StmtCtx
+	date, err := convertDatumToTime(sc, args[0])
+	if err != nil {
+		return d, errorOrWarning(err, b.ctx)
+	}
+	ret := types.TimestampDiff("DAY", types.ZeroDate, date)
+	if ret == 0 {
+		return d, errorOrWarning(types.ErrInvalidTimeFormat, b.ctx)
+	}
+	d.SetInt64(ret)
+	return d, nil
 }
 
 type toSecondsFunctionClass struct {

expression/builtin_time_test.go

@@ -1159,6 +1159,46 @@ func (s *testEvaluatorSuite) TestGetFormat(c *C) {
 		c.Assert(result, Equals, test.expect)
 	}
 }
+
+func (s *testEvaluatorSuite) TestToDays(c *C) {
+	tests := []struct {
+		param  interface{}
+		expect int64
+	}{
+		{950501, 728779},
+		{"2007-10-07", 733321},
+		{"2008-10-07", 733687},
+		{"08-10-07", 733687},
+		{"0000-01-01", 1},
+		{"2007-10-07 00:00:59", 733321},
+	}
+
+	fc := funcs[ast.ToDays]
+	for _, test := range tests {
+		t := []types.Datum{types.NewDatum(test.param)}
+		f, err := fc.getFunction(datumsToConstants(t), s.ctx)
+		c.Assert(err, IsNil)
+		d, err := f.eval(nil)
+		c.Assert(err, IsNil)
+		c.Assert(d.GetInt64(), Equals, test.expect)
+	}
+
+	testsNull := []interface{}{
+		"0000-00-00",
+		"1992-13-00",
+		"2007-10-07 23:59:61",
+		123456789}
+
+	for _, i := range testsNull {
+		t := []types.Datum{types.NewDatum(i)}
+		f, err := fc.getFunction(datumsToConstants(t), s.ctx)
+		c.Assert(err, IsNil)
+		d, err := f.eval(nil)
+		c.Assert(err, IsNil)
+		c.Assert(d.IsNull(), IsTrue)
+	}
+}
+
 func (s *testEvaluatorSuite) TestTimestampAdd(c *C) {
 	tests := []struct {
 		unit     string

plan/typeinferer.go

@@ -358,7 +358,7 @@ func (v *typeInferrer) handleFuncCallExpr(x *ast.FuncCallExpr) {
 		tp = types.NewFieldType(mysql.TypeDatetime)
 	case "microsecond", "second", "minute", "hour", "day", "week", "month", "year",
 		"dayofweek", "dayofmonth", "dayofyear", "weekday", "weekofyear", "yearweek", "datediff",
-		"found_rows", "length", "extract", "locate", "unix_timestamp", "quarter", "is_ipv4":
+		"found_rows", "length", "extract", "locate", "unix_timestamp", "quarter", "is_ipv4", "to_days":
 		tp = types.NewFieldType(mysql.TypeLonglong)
 	case "now", "sysdate", "current_timestamp", "utc_timestamp":
 		tp = types.NewFieldType(mysql.TypeDatetime)

plan/typeinferer_test.go

@@ -244,6 +244,8 @@ func (ts *testTypeInferrerSuite) TestInferType(c *C) {
 		{"sign(null)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
 		{"unix_timestamp()", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
 		{"unix_timestamp('2015-11-13 10:20:19')", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
+		{"to_days('2015-11-13')", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
+		{"to_days(950501)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
 		{"floor(1.23)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
 		{"field('foo', null)", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},
 		{"find_in_set('foo', 'foo,bar')", mysql.TypeLonglong, charset.CharsetBin, mysql.BinaryFlag},