type Check struct {
	Name       string
	Constraint string // length(phone) >= 10
	*Field
}

// ParseCheckConstraints parse schema check constraints
func (schema *Schema) ParseCheckConstraints() map[string]Check {
	checks := map[string]Check{}
	for _, field := range schema.FieldsByDBName {
		if chk := field.TagSettings["CHECK"]; chk != "" {
			names := strings.Split(chk, ",")