gorm系列-删除

目录

• gorm删除

gorm删除

软删除

删除记录

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。

// 删除现有记录
db.delete(&email)
//// delete from emails where id=10;

// 为删除 sql 添加额外的 sql 操作
db.set("gorm:delete_option", "option (optimize for unknown)").delete(&email)
//// delete from emails where id=10 option (optimize for unknown);

package main

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

//1. 定义模型
type user struct {
   gorm.model
   name string
   age byte
   active bool
}

func main() {
   //2. 连接mysql数据库
   db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
   if err != nil {
      panic(err)
   }
   defer db.close()
   //3. 把模型与数据库中的表对应起来
   db.automigrate(&user{})
   //4. 删除
   var u user
   u.id = 1
   db.debug().delete(u)
   //[2020-04-27 16:35:12]  [20.97ms]  update `users` set `deleted_at`='2020-04-27 16:35:12'  where `users`.`deleted_at` is null and `users`.`id` = 1  
   //[1 rows affected or returned ] 
}

func main() {
   //2. 连接mysql数据库
   db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
   if err != nil {
      panic(err)
   }
   defer db.close()
   //3. 把模型与数据库中的表对应起来
   db.automigrate(&user{})
   //4. 删除
   var u user
   u.name = "yike"
   db.debug().delete(u)
   //[2020-04-27 16:38:07]  [20.97ms]  update `users` set `deleted_at`='2020-04-27 16:38:07'  where `users`.`deleted_at` is null  
   //[1 rows affected or returned ] 
}

批量删除

删除全部匹配的记录

db.where("email like ?", "%jinzhu%").delete(email{})
//// delete from emails where email like "%jinzhu%";

db.delete(email{}, "email like ?", "%jinzhu%")
//// delete from emails where email like "%jinzhu%";

////4. 删除
//var u user
//u.name = "yike"
//db.debug().delete(u)
db.debug().where("name=?","zisefeizhu").delete(user{})
//db.debug().delete("age = ?", 21)

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

db.delete(&user)
//// update users set deleted_at="2013-10-29 10:23" where id = 111;

// 批量删除
db.where("age = ?", 20).delete(&user{})
//// update users set deleted_at="2013-10-29 10:23" where age = 20;

// 查询记录时会忽略被软删除的记录
db.where("age = 20").find(&user)
//// select * from users where age = 20 and deleted_at is null;

// unscoped 方法可以查询被软删除的记录
db.unscoped().where("age = 20").find(&users)
//// select * from users where age = 20;

var u1 []user
db.debug().unscoped().where("name = ?","yike").find(&u1)
//[2020-04-27 16:49:05]  [21.96ms]  select * from `users`  where (name = 'yike')  
//[1 rows affected or returned ] 

物理删除

//物理删除
//db.debug().unscoped().where("name = ?", "zisefeizhu").delete(&user{})
db.debug().unscoped().where("name = ?", "yike").delete(&user{})

不使用软删除

package main

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

//1. 定义模型
type user struct {
   //gorm.model
   id int
   name string
   age byte
   active bool
}

func main() {
   //2. 连接mysql数据库
   db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
   if err != nil {
      panic(err)
   }
   defer db.close()
   //3. 把模型与数据库中的表对应起来
   db.automigrate(&user{})
   ////创建记录
   u1 := user{name:"zisefeizhu", age: 22, active: true}
   db.create(&u1)
   u2 := user{name:" jingxing", age: 21, active:false}
   db.create(&u2)
}

package main

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

//1. 定义模型
type user struct {
   //gorm.model
   id int
   name string
   age byte
   active bool
}

func main() {
   //2. 连接mysql数据库
   db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
   if err != nil {
      panic(err)
   }
   defer db.close()
   //3. 把模型与数据库中的表对应起来
   db.automigrate(&user{})
   //删除
   db.debug().where("name=?","zisefeizhu").delete(user{})
}