Gorm 更新操作

Gorm 入门指南

演示样例

package main

import (
    "fmt"
    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/mysql"
)
//  1.  定义模型
type User struct{
    gorm.Model
    Name string
    Age int
    Active bool
}

func main(){
    //  2.  连接数据库
    db , err := gorm.Open("mysql",
        "root:root@(127.0.0.1:3306)/db1?charset=utf8&mb4&parseTime=True&loc=Local")
    if err != nil{
        fmt.Printf("connect DB failed , err : %v\n",err)
        return
    }
    defer db.Close()
    fmt.Printf("连接数据库成功!\n")

    //  3.  数据库的表与模型建立关系
    db.AutoMigrate(User{})

    //  4.  创建数据添加到库中
    db.Create(&User{Name:"Crazy", Age:12, Active:false})
    db.Create(&User{Name:"LiMei", Age:16, Active:true})
    db.Create(&User{Name:"GeLei", Age:20, Active:false})
    db.Create(&User{Name:"Will", Age:30, Active:true})
}

更新 字段

//  6.  更新 - save 必须要获取主键,才能更新对应的行,不然就会生成一条新的创建到表内;

    //  更新所有字段
    //  UPDATE `users` SET `created_at` = '2021-03-09 09:58:27', `updated_at` = '2021-03-09 09:58:27', `deleted_at` = NULL, `name` = 'Ali', `age` = 19, `active` = true  WHERE `users`.`deleted_at` IS NULL AND `users`.`id` = 4
    db.Debug().Save( &user )
    user = User{}

    //  更新修改字段  (根据主键 确定哪一行)
    //  如果你只希望更新指定字段，可以使用Update或者Updates

    //  UPDATE `users` SET `name` = 'hello', `updated_at` = '2021-03-09 09:58:27'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model( &user ).Update("name", "hello1")

    // 根据给定的条件更新单个属性
    //  UPDATE `users` SET `name` = 'hello2', `updated_at` = '2021-03-09 10:07:38'  WHERE `users`.`deleted_at` IS NULL AND  ((active = true))
    db.Debug().Model( &user ).Where("active = ?", true).Update("name", "hello2")

    // 使用 map 更新多个属性，只会更新其中有变化的属性
    //  UPDATE `users` SET `active` = false, `age` = 18, `name` = 'hello3', `updated_at` = '2021-03-09 10:14:26'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model( &user ).Updates(map[string]interface{}{"name": "hello3", "age": 18, "active": false})

    // 使用 struct 更新多个属性，只会更新其中有变化且为非零值的字段
    // UPDATE `users` SET `age` = 18, `name` = 'hello4', `updated_at` = '2021-03-09 10:15:34'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model( &user ).Updates(User{Name: "hello4", Age: 18})

    // 警告：当使用 struct 更新时，GORM只会更新那些非零值的字段
    // 对于下面的操作，不会发生任何更新，"", 0, false 都是其类型的零值
    // 不执行
    db.Debug().Model( &user ).Updates(User{Name: "", Age: 0, Active: false})

    //  6.  更新

    //  更新选定字段
    user = User{}
    //  UPDATE `users` SET `name` = 'hello5', `updated_at` = '2021-03-09 10:31:35'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).Select("name").Updates(map[string]interface{}{"name": "hello5", "age": 18, "active": false})

    //  UPDATE `users` SET `active` = false, `age` = 22, `updated_at` = '2021-03-09 10:36:55'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).Omit("name").Updates(map[string]interface{}{"name": "hello6", "age": 22, "active": false})

    //  无Hooks更新
    // 更新单个属性，类似于 `Update`
    //  UPDATE `users` SET `name` = 'hello7'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).UpdateColumn("name", "hello7")


    // 更新多个属性，类似于 `Updates`
    //  UPDATE `users` SET `age` = 18, `name` = 'hello8'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).UpdateColumns(User{Name: "hello8", Age: 18})

    //  UPDATE `users` SET `age` = 18, `name` = 'hello9'  WHERE (id IN (3,4))
    db.Debug().Table("users").Where("id IN (?)", []int{3, 4}).Updates(map[string]interface{}{"name": "hello9", "age": 18})
    //// UPDATE users SET name='hello', age=18 WHERE id IN (10, 11);

    // 使用 struct 更新时，只会更新非零值字段，若想更新所有字段，请使用map[string]interface{}
    //  UPDATE `users` SET `age` = 18, `name` = 'hello10', `updated_at` = '2021-03-09 10:40:34'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(User{}).Updates(User{Name: "hello10", Age: 18})

    // 使用 `RowsAffected` 获取更新记录总数
    //  UPDATE `users` SET `age` = 18, `name` = 'hello11', `updated_at` = '2021-03-09 10:41:16'  WHERE `users`.`deleted_at` IS NULL
    //  rows = 4
    rows := db.Debug().Model(User{}).Updates(User{Name: "hello11", Age: 18}).RowsAffected
    fmt.Printf("%d\n",rows)

    //  UPDATE `users` SET `age` = age * 2 + 100, `updated_at` = '2021-03-09 10:42:14'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).Update("age", gorm.Expr("age * ? + ?", 2, 100))

    //  UPDATE `users` SET `age` = age * 2 + 100, `updated_at` = '2021-03-09 10:42:14'  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).Updates(map[string]interface{}{"age": gorm.Expr("age * ? + ?", 2, 100)})

    //  UPDATE `users` SET `age` = age - 1  WHERE `users`.`deleted_at` IS NULL
    db.Debug().Model(&user).UpdateColumn("age", gorm.Expr("age - ?", 1))

    //  UPDATE `users` SET `age` = age - 1  WHERE `users`.`deleted_at` IS NULL AND ((age > 10))
    db.Debug().Model(&user).Where("age > 10").UpdateColumn("age", gorm.Expr("age - ?", 1))