func builtinNow(args []types.Datum, ctx context.Context) (d types.Datum, err error) {
// TODO: if NOW is used in stored function or trigger, NOW will return the beginning time
// of the execution.
fsp := 0
sc := ctx.GetSessionVars().StmtCtx
if len(args) == 1 && !args[0].IsNull() {
if fsp, err = checkFsp(sc, args[0]); err != nil {
d.SetNull()
return d, errors.Trace(err)
}
}
tr, err := types.RoundFrac(time.Now(), int(fsp))
if err != nil {
d.SetNull()
return d, errors.Trace(err)
}
t := types.Time{
Time: types.FromGoTime(tr),
Type: mysql.TypeDatetime,
// set unspecified for later round
Fsp: fsp,
}
d.SetMysqlTime(t)
return d, nil
}
// See http://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_from-unixtime
func builtinFromUnixTime(args []types.Datum, ctx context.Context) (d types.Datum, err error) {
sc := ctx.GetSessionVars().StmtCtx
unixTimeStamp, err := args[0].ToDecimal(sc)
if err != nil {
return d, errors.Trace(err)
}
// 0 <= unixTimeStamp <= INT32_MAX
if unixTimeStamp.IsNegative() {
return
}
integralPart, err := unixTimeStamp.ToInt()
if err == types.ErrTruncated {
err = nil
}
if err != nil {
return d, errors.Trace(err)
}
if integralPart > int64(math.MaxInt32) {
return
}
// Split the integral part and fractional part of a decimal timestamp.
// e.g. for timestamp 12345.678,
// first get the integral part 12345,
// then (12345.678 - 12345) * (10^9) to get the decimal part and convert it to nanosecond precision.
integerDecimalTp := new(types.MyDecimal).FromInt(integralPart)
fracDecimalTp := new(types.MyDecimal)
err = types.DecimalSub(unixTimeStamp, integerDecimalTp, fracDecimalTp)
if err != nil {
return d, errors.Trace(err)
}
nano := new(types.MyDecimal).FromInt(int64(time.Second))
x := new(types.MyDecimal)
err = types.DecimalMul(fracDecimalTp, nano, x)
if err != nil {
return d, errors.Trace(err)
}
fractionalPart, err := x.ToInt() // here fractionalPart is result multiplying the original fractional part by 10^9.
if err == types.ErrTruncated {
err = nil
}
if err != nil {
return d, errors.Trace(err)
}
_, fracDigitsNumber := unixTimeStamp.PrecisionAndFrac()
fsp := fracDigitsNumber
if fracDigitsNumber > types.MaxFsp {
fsp = types.MaxFsp
}
tr, err := types.RoundFrac(time.Unix(integralPart, fractionalPart), fsp)
if err != nil {
return d, errors.Trace(err)
}
t := types.Time{
Time: types.FromGoTime(tr),
Type: mysql.TypeDatetime,
Fsp: fsp,
}
if args[0].Kind() == types.KindString { // Keep consistent with MySQL.
t.Fsp = types.MaxFsp
}
d.SetMysqlTime(t)
if len(args) == 1 {
return
}
return builtinDateFormat([]types.Datum{d, args[1]}, ctx)
}