使用SQL语句进行查询

使用SQL语句进行查询

使用 Raw SQL 查询，无需使用 ORM 表定义
多数据库，都可直接使用占位符号 ?，自动转换
查询时的参数，支持使用 Model Struct 和 Slice, Array

o := orm.NewOrm()
ids := []int{1, 2, 3}
var r RawSter
r = o.Raw("SELECT name FROM user WHERE id IN (?, ?, ?)", ids)

创建一个 RawSeter

o := orm.NewOrm()
var r RawSeter
r = o.Raw("UPDATE user SET name = ? WHERE name = ?", "testing", "slene")


// RawSeter raw query seter
// create From Ormer.Raw
// for example:
//  sql := fmt.Sprintf("SELECT %sid%s,%sname%s FROM %suser%s WHERE id = ?",Q,Q,Q,Q,Q,Q)
//  rs := Ormer.Raw(sql, 1)
type RawSeter interface {
    // execute sql and get result
    Exec() (sql.Result, error)
    // query data and map to container
    // for example:
    //    var name string
    //    var id int
    //    rs.QueryRow(&id,&name) // id==2 name=="slene"
    QueryRow(containers ...interface{}) error
    // query data rows and map to container
    //    var ids []int
    //    var names []int
    //    query = fmt.Sprintf("SELECT 'id','name' FROM %suser%s", Q, Q)
    //    num, err = dORM.Raw(query).QueryRows(&ids,&names) // ids=>{1,2},names=>{"nobody","slene"}
    QueryRows(containers ...interface{}) (int64, error)
    SetArgs(...interface{}) RawSeter
    // query data to []map[string]interface
    // see QuerySeter's Values
    Values(container *[]Params, cols ...string) (int64, error)
    // query data to [][]interface
    // see QuerySeter's ValuesList
    ValuesList(container *[]ParamsList, cols ...string) (int64, error)
    // query data to []interface
    // see QuerySeter's ValuesFlat
    ValuesFlat(container *ParamsList, cols ...string) (int64, error)
    // query all rows into map[string]interface with specify key and value column name.
    // keyCol = "name", valueCol = "value"
    // table data
    // name  | value
    // total | 100
    // found | 200
    // to map[string]interface{}{
    //     "total": 100,
    //     "found": 200,
    // }
    RowsToMap(result *Params, keyCol, valueCol string) (int64, error)
    // query all rows into struct with specify key and value column name.
    // keyCol = "name", valueCol = "value"
    // table data
    // name  | value
    // total | 100
    // found | 200
    // to struct {
    //     Total int
    //     Found int
    // }
    RowsToStruct(ptrStruct interface{}, keyCol, valueCol string) (int64, error)
    // return prepared raw statement for used in times.
    // for example:
    //     pre, err := dORM.Raw("INSERT INTO tag (name) VALUES (?)").Prepare()
    //     r, err := pre.Exec("name1") // INSERT INTO tag (name) VALUES (`name1`)
    Prepare() (RawPreparer, error)
}

Exec

执行 sql 语句，返回 sql.Result 对象

res, err := o.Raw("UPDATE user SET name = ?", "your").Exec()
if err == nil {
    num, _ := res.RowsAffected()
    fmt.Println("mysql row affected nums: ", num)
}

QueryRow

QueryRow 和 QueryRows 提供高级 sql mapper 功能

支持 struct

type User struct {
    Id       int
    UserName string
}
var user User
err := o.Raw("SELECT id, user_name FROM user WHERE id = ?", 1).QueryRow(&user)

QueryRows

QueryRows 支持的对象还有 map 规则是和 QueryRow 一样的，但都是 slice

type User struct {
    Id       int
    UserName string
}
var users []User
num, err := o.Raw("SELECT id, user_name FROM user WHERE id = ?", 1).QueryRows(&users)
if err == nil {
    fmt.Println("user nums: ", num)
}

SetArgs

改变 Raw(sql, args…) 中的 args 参数，返回一个新的 RawSeter

用于单条 sql 语句，重复利用，替换参数然后执行。

res, err := r.SetArgs("arg1", "arg2").Exec()
res, err := r.SetArgs("arg1", "arg2").Exec()
...

Values / ValuesList / ValuesFlat

Raw SQL 查询获得的结果集 Value 为 string 类型，NULL 字段的值为空 ``

Values

返回结果集的 key => value 值

var maps []orm.Params
num, err := o.Raw("SELECT user_name FROM user WHERE status = ?", 1).Values(&maps)
if err == nil && num > 0 {
    fmt.Println(maps[0]["user_name"]) // slene
}

ValuesList

返回结果集 slice

var lists []orm.ParamsList
num, err := o.Raw("SELECT user_name FROM user WHERE status = ?", 1).ValuesList(&lists)
if err == nil && num > 0 {
    fmt.Println(lists[0][0]) // slene
}

ValuesFlat

返回单一字段的平铺 slice 数据

var list orm.ParamsList
num, err := o.Raw("SELECT id FROM user WHERE id < ?", 10).ValuesFlat(&list)
if err == nil && num > 0 {
    fmt.Println(list) // []{"1","2","3",...}
}

RowsToMap

SQL 查询结果是这样

name	value
total	100
found	200

查询结果匹配到 map 里

res := make(orm.Params)
nums, err := o.Raw("SELECT name, value FROM options_table").RowsToMap(&res, "name", "value")
// res is a map[string]interface{}{
//    "total": 100,
//    "found": 200,
// }

RowsToStruct