gorm系列-刪除

目錄

• Gorm刪除
  • 刪除記錄
  • 批量刪除
  • 軟刪除
  • 物理刪除
  • 不使用軟刪除

Gorm刪除

軟刪除

刪除記錄

警告 刪除記錄時，請確保主鍵字段有值，GORM 會通過主鍵去刪除記錄，如果主鍵為空，GORM 會刪除該 model 的所有記錄。

// 刪除現有記錄
db.Delete(&email)
//// DELETE from emails where id=10;

// 為刪除 SQL 添加額外的 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. 定義模型
type User struct {
   gorm.Model
   Name string
   Age byte
   Active bool
}

func main() {
   //2. 連接Mysql數據庫
   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. 把模型與數據庫中的表對應起來
   db.AutoMigrate(&User{})
   //4. 刪除
   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. 連接Mysql數據庫
   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. 把模型與數據庫中的表對應起來
   db.AutoMigrate(&User{})
   //4. 刪除
   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 ] 
}

批量刪除

刪除全部匹配的記錄

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. 刪除
//var u User
//u.Name = "yike"
//db.Debug().Delete(u)
db.Debug().Where("name=?","zisefeizhu").Delete(User{})
//db.Debug().Delete("age = ?", 21)

軟刪除

如果一個 model 有 DeletedAt 字段，他將自動獲得軟刪除的功能！ 當調用 Delete 方法時， 記錄不會真正的從數據庫中被刪除， 只會將DeletedAt 字段的值會被設置為當前時間

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

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

// 查詢記錄時會忽略被軟刪除的記錄
db.Where("age = 20").Find(&user)
//// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL;

// Unscoped 方法可以查詢被軟刪除的記錄
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 ] 

物理刪除

//物理刪除
//db.Debug().Unscoped().Where("name = ?", "zisefeizhu").Delete(&User{})
db.Debug().Unscoped().Where("name = ?", "yike").Delete(&User{})

不使用軟刪除

package main

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

//1. 定義模型
type User struct {
   //gorm.Model
   ID int
   Name string
   Age byte
   Active bool
}

func main() {
   //2. 連接Mysql數據庫
   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. 把模型與數據庫中的表對應起來
   db.AutoMigrate(&User{})
   ////創建記錄
   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. 定義模型
type User struct {
   //gorm.Model
   ID int
   Name string
   Age byte
   Active bool
}

func main() {
   //2. 連接Mysql數據庫
   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. 把模型與數據庫中的表對應起來
   db.AutoMigrate(&User{})
   //刪除
   db.Debug().Where("name=?","zisefeizhu").Delete(User{})
}