使用ORM的时候我们可以采用QueryBuilder 去构造SQL
qb的接口
// QueryBuilder is the Query builder interface
type QueryBuilder interface {
Select(fields ...string) QueryBuilder
ForUpdate() QueryBuilder
From(tables ...string) QueryBuilder
InnerJoin(table string) QueryBuilder
LeftJoin(table string) QueryBuilder
RightJoin(table string) QueryBuilder
On(cond string) QueryBuilder
Where(cond string) QueryBuilder
And(cond string) QueryBuilder
Or(cond string) QueryBuilder
In(vals ...string) QueryBuilder
OrderBy(fields ...string) QueryBuilder
Asc() QueryBuilder
Desc() QueryBuilder
Limit(limit int) QueryBuilder
Offset(offset int) QueryBuilder
GroupBy(fields ...string) QueryBuilder
Having(cond string) QueryBuilder
Update(tables ...string) QueryBuilder
Set(kv ...string) QueryBuilder
Delete(tables ...string) QueryBuilder
InsertInto(table string, fields ...string) QueryBuilder
Values(vals ...string) QueryBuilder
Subquery(sub string, alias string) string
String() string
}
通过上面的接口我们可以看到 QueryBuilder 返回值也是一个QueryBuilder ,所以我们可以像平时写SQL构建自己的SQL解析语句
orm.RegisterDataBase("default", "mysql", "root:123456@tcp(127.0.0.1:3306)/test?charset=utf8", 30)
orm.RegisterModel(new(UserInfo))
o := orm.NewOrm()
上面代码 ,链接了数据库,创建了RegisterModel ,创建了Orm对象
接着创建QueryBuilder
qb, _ := orm.NewQueryBuilder("mysql")
目前支持以下四种数据库初始化
// NewQueryBuilder return the QueryBuilder
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
}
构造sql语句
qb.Select("*").From("user_info")
sql := qb.String()
执行sql
o.Raw(sql).QueryRows(&user)