func computeDiv(a, b types.Datum) (d types.Datum, err error) {
// MySQL support integer divison Div and division operator /
// we use opcode.Div for division operator and will use another for integer division later.
// for division operator, we will use float64 for calculation.
switch a.Kind() {
case types.KindFloat64:
y, err1 := b.ToFloat64()
if err1 != nil {
return d, errors.Trace(err1)
}
if y == 0 {
return d, nil
}
x := a.GetFloat64()
d.SetFloat64(x / y)
return d, nil
default:
// the scale of the result is the scale of the first operand plus
// the value of the div_precision_increment system variable (which is 4 by default)
// we will use 4 here
xa, err1 := a.ToDecimal()
if err != nil {
return d, errors.Trace(err1)
}
xb, err1 := b.ToDecimal()
if err1 != nil {
return d, errors.Trace(err1)
}
if f, _ := xb.Float64(); f == 0 {
// division by zero return null
return d, nil
}
d.SetMysqlDecimal(xa.Div(xb))
return d, nil
}
}