golang ：ORM之 QueryBuilder

// QueryBuilder is the Query builder interface
type QueryBuilder interface {
    Select(fields ...string) QueryBuilde
    ForUpdate() QueryBuilde
    From(tables ...string) QueryBuilde
    InnerJoin(table string) QueryBuilde
    LeftJoin(table string) QueryBuilde
    RightJoin(table string) QueryBuilde
    On(cond string) QueryBuilde
    Where(cond string) QueryBuilde
    And(cond string) QueryBuilde
    Or(cond string) QueryBuilde
    In(vals ...string) QueryBuilde
    OrderBy(fields ...string) QueryBuilde
    Asc() QueryBuilde
    Desc() QueryBuilde
    Limit(limit int) QueryBuilde
    Offset(offset int) QueryBuilde
    GroupBy(fields ...string) QueryBuilde
    Having(cond string) QueryBuilde
    Update(tables ...string) QueryBuilde
    Set(kv ...string) QueryBuilde
    Delete(tables ...string) QueryBuilde
    InsertInto(table string, fields ...string) QueryBuilde
    Values(vals ...string) QueryBuilde
    Subquery(sub string, alias string) string
    String() string
}

    orm.RegisterDataBase("default","mysql","root:123456@tcp(127.0.0.1:3306)/test?charset=utf8",30)
    orm.RegisterModel(new(UserInfo))
    o := orm.NewOrm()

qb, _ := orm.NewQueryBuilder("mysql")

// NewQueryBuilder return the QueryBuilde
func NewQueryBuilder(driver string) (qb QueryBuilder, err error) {
    if driver == "mysql" {
        qb = new(MySQLQueryBuilder)
    } else if driver == "tidb" {
        qb = new(TiDBQueryBuilder)
    } else if driver == "postgres" {
        err = errors.New("postgres query builder is not supported yet")
    } else if driver == "sqlite" {
        err = errors.New("sqlite query builder is not supported yet")
    } else {
        err = errors.New("unknown driver for query builder")
    }
    return
}

qb.Select("*").From("user_info")
sql := qb.String()

o.Raw(sql).QueryRows(&user)