GORM模型删除

GORM模型删除

一、删除记录

package main

import (
	"fmt"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type UsersUpdate struct {
	gorm.Model
	//Name *string `gorm:"type:varchar(100);default:RandySun;comment:姓名"`
	Name string `gorm:"type:varchar(100);default:RandySun;comment:姓名"`
	Age  int64
	// 设置默认值
	Active bool
}

func main() {
	dsn := "root:@tcp(127.0.0.1:3306)/gorm?charset=utf8mb4&parseTime=True&loc=Local"
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	if err != nil {
		panic(err)
	}
	// 迁移表创建对应关系
	db.AutoMigrate(&UsersUpdate{})

	// 添加数据
	db.Debug().Create(&UsersUpdate{Name: "bary", Age: 18})
	db.Debug().Create(&UsersUpdate{Name: "RandySun", Age: 18})
	db.Debug().Create(&UsersUpdate{Name: "Jack", Age: 18})
	db.Debug().Create(&UsersUpdate{Name: "", Age: 19}) // 添加记录name默认为Null
	
	//// 查询
	var user UsersUpdate
	db.Debug().First(&user)
	fmt.Printf("%#v", user)

}

警告 删除记录时，请确保主键字段有值，GORM 会通过主键去删除记录，如果主键为空，GORM 会删除该 model 的所有记录。

var user UsersUpdate
db.Debug().First(&user)
fmt.Printf("%#v", user)
// 删除现有记录
//  UPDATE `users_updates` SET `deleted_at`='2021-11-24 09:07:51.079' WHERE `users_updates`.`id` = 1 AND `users_updates`.`deleted_at` IS NULL
db.Debug().Delete(&user)

// 为删除 SQL 添加额外的 SQL 操作
// DELETE from emails where id=10 OPTION (OPTIMIZE FOR UNKNOWN);
db.Set("gorm:delete_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Delete(&email)

二、批量删除

删除全部匹配的记录

var user UsersUpdate
db.Debug().First(&user)
fmt.Printf("%#v", user)
//  UPDATE `users_updates` SET `deleted_at`='2021-11-24 22:10:16.311' WHERE name LIKE '%he%' AND `users_updates`.`id` = 1 AND `users_updates`.
`deleted_at` IS NULL
db.Debug().Where("name LIKE ?", "%he%").Delete(&user)

// DELETE from `users_updates` where name LIKE "%Randy%";
db.Debug().Delete(UsersUpdate{}, "name LIKE ?", "%Randy%")

三、软删除

如果一个 model 有 DeletedAt 字段，他将自动获得软删除的功能！ 当调用 Delete 方法时， 记录不会真正的从数据库中被删除， 只会将DeletedAt 字段的值会被设置为当前时间

// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE id = 111;
db.Delete(&user)


// 批量删除
// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE age = 20;
db.Where("age = ?", 20).Delete(&User{})


// 查询记录时会忽略被软删除的记录
// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL;
db.Where("age = 20").Find(&user)


// Unscoped 方法可以查询被软删除的记录
// SELECT * FROM users WHERE age = 20;
db.Unscoped().Where("age = 20").Find(&users)

四、物理删除

// Unscoped 方法可以物理删除记录
//// DELETE FROM orders WHERE id=10;
db.Unscoped().Delete(&order)