func (qb *MySQLQueryBuilder) ForUpdate() QueryBuilder {
	qb.Tokens = append(qb.Tokens, "FOR UPDATE")
	return qb
}
ForUpdate add the FOR UPDATE clause
package orm
import (
	"fmt"
	"strconv"
	"strings"
)
const CommaSpace = ", "
type MySQLQueryBuilder struct {
	Tokens []string
}
func (qb *MySQLQueryBuilder) Select(fields ...string) QueryBuilder {
	qb.Tokens = append(qb.Tokens, "SELECT", strings.Join(fields, CommaSpace))
	return qb
}