gorm 操作

前提

• gorm中文官方文档http://gorm.book.jasperxu.com/advanced.html#cpk

    go get  github.com/jinzhu/gorm

增删改查实例代码

package main

import (
    "fmt"
    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/mysql"
    "log"
    "time"
)

var db *gorm.DB


type User struct {
    User_id   int `gorm:"primary_key"` //指定主键并自增
    Name      string
    Pwd       string
    CreatedAt time.Time
    UpdatedAt time.Time
    Car       []Car `gorm:"ForeignKey:User_id;AssociationForeignKey:User_id"` //(一对多)指定外键和关联外键
}

type Car struct {
    Car_id     int32 `gorm:"primary_key"`
    User_id    int
    Car_name   string
    Car_gongli string
    Proce int
}


func allError(err error){
    if err!=nil{
        log.Println(err.Error())
    }
}

func Create_table(){
    //一个坑，不设置这个参数，gorm会把表名转义后加个s，导致找不到数据库的表
    db.SingularTable(true)
    //自动迁移模式 有表不创 无表创表 少列加列 有列不加
    db.AutoMigrate(&User{},&Car{})
}

func Select(){
    user := User{}
    //日志调试模式
    db.LogMode(true)

    //
    db.SingularTable(true)
    //db.First(&user, 1)

    //关联查询 一对多
    db.Where("Name = ?","owen").Preload("Car").Find(&user)
    //执行了 SELECT * FROM `user`  WHERE (Name = 'owen') SELECT * FROM `car`  WHERE (`user_id` IN (1))
    fmt.Println(user)

    db.Where("user_id = ?", 1).Preload("Car").Find(&user)
    //执行了 SELECT * FROM `user`  WHERE (user_id = 1)  SELECT * FROM `car`  WHERE (`user_id` IN (1))
    fmt.Println(user)

    //关联查询多对一
    db.Where("user_id = ?", 1).Preload("Car","car_name like ?","%本%").Find(&user)
    //执行了 SELECT * FROM `user`  WHERE (user_id = 1)  SELECT * FROM `car`  WHERE (`user_id` IN (1)) AND (car_name like '%本%')
    fmt.Println(user)
}

func Updata(){
    user:=User{}
    //日志调试模式
    //db.LogMode(true)
    db.SingularTable(true)

    //选择字段更新的两种模式
    err:=db.Model(&user).Where("Name = ?","hello").Updates(User{Name: "owen", Pwd: "1323"}).Error
    allError(err)

    err=db.Model(&user).Where("name = ?","owen").UpdateColumns(User{Name: "hello", Pwd: "1323"}).Error
    allError(err)
}

func Delete(){
    user:=User{}
    db.SingularTable(true)
    //删除指定的
    err:=db.Delete(user,"name = ? and pwd = ?","owen","1323").Error
    allError(err)
}

func Insert() {
    db.SingularTable(true)
    user := User{Name: "Jinzhu", Pwd: "123421"}
    err := db.Create(&user).Error
    allError(err)
}


func init() {
    var err error
    db, err = gorm.Open("mysql", "user:pw@tcp(localhost:3306)/dbname?charset=utf8&parseTime=True&loc=Local")
    //defer db.Close()
    allError(err)
}


  func main() {
    Create_table()
    Insert()
    Select()
    Updata()
    Delete()
}

2.1gorm 关联查询

//数据库的表结构
type User struct {
    User_id   int `gorm:"primary_key;comment:'id'""` //指定主键并自增
    Name      string`gorm:"varchar(30);comment:'姓名'"`
    Pwd       string`gorm:"varchar(30);comment:'密码'"`
    CreatedAt time.Time `gorm:"comment:'创建时间'"`
    UpdatedAt time.Time `gorm:"comment:'更新时间'"`
}

type Class struct {
    Id int
    Class string `gorm:"varchar(255)"`
}


type Result struct {
    User_id    string `json:"Id"`
    Class  string `json:"class"`
    Name   string `json:"Name"`
    Pwd string `json:"pwd"`
}

//关联查询数据
func Select() []Result{
    db.SingularTable(true)
    db.LogMode(true)
    var result []Result

    db.Table("user").Select("user_id,name,pwd,class").Joins("left join class on class.id=user.user_id").Scan(&result)
    return result
}

3、后言

• 支持的数据库
  mysql 注意： 为了正确的处理 time.Time ，你需要包含 parseTime 作为参数。 (More supported parameters)

  import (
  "github.com/jinzhu/gorm"
  _ "github.com/jinzhu/gorm/dialects/mysql"
    )
  func main() {
  db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
  defer db.Close()
    }
  

pgsql:

    import (
    "github.com/jinzhu/gorm"
  _ "github.com/jinzhu/gorm/dialects/postgres"
  )

func main() {
    db, err := gorm.Open("postgres", "host=myhost port=myport user=gorm dbname=gorm  password=mypassword")
      defer db.Close()
    }

sqlite:

    import (
    "github.com/jinzhu/gorm"
  _ "github.com/jinzhu/gorm/dialects/sqlite"
  )

  func main() {
    db, err := gorm.Open("sqlite3", "/tmp/gorm.db")
    defer db.Close()
  }

sqlserver:

  import (
  "github.com/jinzhu/gorm"
  _ "github.com/jinzhu/gorm/dialects/mssql"
  )

  func main() {
  db, err := gorm.Open("mssql", "sqlserver://username:password@localhost:1433?database=dbname")
    defer db.Close()
  }