func getDefaultValue(c *ConstraintOpt, tp byte, fsp int) (interface{}, error) {
if tp == mysql.TypeTimestamp || tp == mysql.TypeDatetime {
value, err := expressions.GetTimeValue(nil, c.Evalue, tp, fsp)
if err != nil {
return nil, errors.Trace(err)
}
// Value is nil means `default null`.
if value == nil {
return nil, nil
}
// If value is mysql.Time, convert it to string.
if vv, ok := value.(mysql.Time); ok {
return vv.String(), nil
}
return value, nil
}
return expressions.FastEval(c.Evalue), nil
}
// Plan gets SrcPlan/SelectFieldsDefaultPlan.
// If all fields are equal to src plan fields, then gets SrcPlan.
// Default gets SelectFieldsDefaultPlan.
func (r *SelectFieldsRset) Plan(ctx context.Context) (plan.Plan, error) {
fields := r.SelectList.Fields
srcFields := r.Src.GetFields()
if len(fields) == len(srcFields) {
match := true
for i, v := range fields {
// TODO: is it this check enough? e.g, the ident field is t.c.
if x, ok := v.Expr.(*expressions.Ident); ok && strings.EqualFold(x.L, srcFields[i].Name) && strings.EqualFold(v.Name, srcFields[i].Name) {
continue
}
match = false
break
}
if match {
return r.Src, nil
}
}
src := r.Src
if x, ok := src.(*plans.TableDefaultPlan); ok {
// check whether src plan will be set TableNilPlan, like `select 1, 2 from t`.
isConst := true
for _, v := range fields {
if expressions.FastEval(v.Expr) == nil {
isConst = false
break
}
}
if isConst {
src = &plans.TableNilPlan{T: x.T}
}
}
p := &plans.SelectFieldsDefaultPlan{Src: src, SelectList: r.SelectList}
return p, nil
}