GORM学习入门

文章介绍

在篇内容介绍基于golang的gorm,这里我将简单介绍如何安装，连接数据库(以MySQL为例)，以及基本的curd操作

安装

 
go get -u gorm.io/gorm
go get -u gorm.io/driver/sqlite

模型定义

模型是标准的 struct，由 Go 的基本数据类型、实现了 Scanner 和 Valuer 接口的自定义类型及其指针或别名组成，我们最后的表名就是结构体的和结构体名一致，当然字段也一致的

例如：

 
type User struct {
  ID           uint
  Name         string
  Email        *string
  Age          uint8
  Birthday     *time.Time
  MemberNumber sql.NullString
  ActivatedAt  sql.NullTime
  CreatedAt    time.Time
  UpdatedAt    time.Time
}

GORM 倾向于约定，而不是配置。默认情况下，GORM 使用 ID 作为主键，使用结构体名的 蛇形复数 作为表名，字段名的 蛇形 作为列名，并使用 CreatedAt、UpdatedAt 字段追踪创建、更新时间

当然，遵循 GORM 已有的约定，可以减少您的配置和代码量。如果约定不符合您的需求，GORM 允许您自定义配置它们

自定义配置

使用 `ID` 作为主键

默认情况下，GORM 会使用 ID 作为表的主键。

 
type User struct {
  ID   string // 默认情况下，名为 `ID` 的字段会作为表的主键
  Name string
}

你可以通过标签 primaryKey 将其它字段设为主键

 
// 将 `UUID` 设为主键
type Animal struct {
  ID     int64
  UUID   string `gorm:"primaryKey"`
  Name   string
  Age    int64
}

此外，您还可以看看复合主键

gorm.Model

GORM 定义一个 gorm.Model 结构体，其包括字段 ID、CreatedAt、UpdatedAt、DeletedAt

 
// gorm.Model 的定义
type Model struct {
  ID        uint           `gorm:"primaryKey"`
  CreatedAt time.Time
  UpdatedAt time.Time
  DeletedAt gorm.DeletedAt `gorm:"index"`
}

您可以将它嵌入到您的结构体中，以包含这几个字段

连接数据库

这里我们以mysql为例：

 
import (
  "gorm.io/driver/mysql" 
  "gorm.io/gorm"
)
 
func main() {
  // 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
  dsn := "user:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local" 
  //注意：pass为MySQL数据库的管理员密码，dbname为要连接的数据库
  db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
}

MySQl 驱动程序提供了一些高级配置可以在初始化过程中使用

建表

这里我们先连接数据库，为了方便查看SQL语句，我们将记入日志

 
package main
 
import (
    "log" 
    "os" 
    "time"
 
    "gorm.io/driver/mysql" 
    "gorm.io/gorm" 
    "gorm.io/gorm/logger"
)
 
//定义表结构
type Producttest struct {
    gorm.Model
    Name  string
    Code  string
    Price uint
}
 
func main() {
    // 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
    dsn := "root:Qq/2013XiaoKUang@tcp(127.0.0.1:3306)/gorm_test?charset=utf8mb4&parseTime=True&loc=Local"
 
    //用于输出使用的sql语句
    newLogger := logger.New(
        log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）
        logger.Config{
            SlowThreshold:             time.Second, // 慢 SQL 阈值
            LogLevel:                  logger.Info, // 日志级别
            IgnoreRecordNotFoundError: true,        // 忽略ErrRecordNotFound（记录未找到）错误
            Colorful:                  true,        // 禁用彩色打印
        },
    )
 
    //打开mysql服务中对应的数据库
    db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
        Logger: newLogger,
    })
    if err != nil {
        panic(err)
    }
 
    //AutoMigrate 为给定模式运行自动迁移,建立Product类型的数据表
    err = db.AutoMigrate(&Producttest{})
    if err != nil {
        log.Fatal("建表失败", err)
    }

我们看到建表成功：

mysql> show tables;

+———————+

| Tables_in_gorm_test |

+———————+

| dities |

| products |

| producttests |

| subways |

| test |

| test1 |

| user2 |

| user_infos |

| users |

+———————+

9 rows in set (0.00 sec)

快速入门

新增数据

这里以结构体的方式插入数据

 
    // Create 新增数据
    db.Create(&Producttest{Code: "01", Name: "golang程序设计", Price: 100})
    db.Create(&Producttest{Code: "02", Name: "python入门", Price: 200})

然后我们可以看到输出结果:

 
2022/06/23 09:31:03 /Users/feng/go/src/GormStart/ch01/main.go:51
[16.193ms] [rows:1] INSERT INTO `producttests` (`created_at`,`updated_at`,`deleted_at`,`name`,`code`,`price`) VALUES ('2022-06-23 09:31:03.35','2022-06-23 09:31:03.35',NULL,'golang程序设计','01',100)
 
2022/06/23 09:31:03 /Users/feng/go/src/GormStart/ch01/main.go:52
[2.331ms] [rows:1] INSERT INTO `producttests` (`created_at`,`updated_at`,`deleted_at`,`name`,`code`,`price`) VALUES ('2022-06-23 09:31:03.364','2022-06-23 09:31:03.364',NULL,'python入门','02',200)
Process 96312 has exited with status 0
Detaching
dlv dap (96294) exited with code: 0

这样我们就将两条数据插入了数据库中

查找数据

 
var product Producttest  //需要实例化一个表结构
    db.First(&product, 2) // 根据整型主键查找
    fmt.Println(product.Name)
    db.First(&product, "code = ?", "02") // 查找 code 字段值为 D42 的记录
    fmt.Println(product)

查询结果：

 
[3.323ms] [rows:1] SELECT * FROM `producttests` WHERE `producttests`.`id` = 2 AND `producttests`.`deleted_at` IS NULL ORDER BY `producttests`.`id` LIMIT 1
python入门
 
[1.002ms] [rows:1] SELECT * FROM `producttests` WHERE code = '02' AND `producttests`.`deleted_at` IS NULL AND `producttests`.`id` = 2 ORDER BY `producttests`.`id` LIMIT 1
{{2 2022-06-23 09:31:03.364 +0800 CST 2022-06-23 09:31:03.364 +0800 CST {0001-01-01 00:00:00 +0000 UTC false}} python入门 02 200}

更新数据

 
db.Model(&Producttest{}).Where("Code = ?", "01").Update("Price", "50")
// UPDATE users SET Price='50', updated_at='2022-06-23 10:00:23.654' WHERE Code='01';

输出结果:


[9.204ms] [rows:0] UPDATE `producttests` SET `price`='50',`updated_at`='2022-06-23 10:05:49.719' WHERE Code = '01' AND `producttests`.`deleted_at` IS NULL

删除数据

 
var product Producttest
db.Delete(&product, 1) //删除主码为1的数据

新增数据(C)

我们先定义表结构

 
type User struct {
    Name     string
    Age      uint
    Birthday time.Time
  Addr     string
  Work     string
}

连接数据库：

 
func main() {
    // 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
    dsn := "root:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"
 
    //用于输出使用的sql语句
    newLogger := logger.New(
        log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）
        logger.Config{
            SlowThreshold:             time.Second, // 慢 SQL 阈值
            LogLevel:                  logger.Info, // 日志级别
            IgnoreRecordNotFoundError: true,        // 忽略ErrRecordNotFound（记录未找到）错误
            Colorful:                  true,        // 禁用彩色打印
        },
    )
 
    //打开mysql服务中对应的数据库
    db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
        Logger: newLogger,
    })
    if err != nil {
        panic(err)
    }
 
      //建立表
    _ = db.AutoMigrate(&User{})

建表成功：


[18.454ms] [rows:0] CREATE TABLE `users` (`name` longtext,`age` bigint unsigned,`birthday` datetime(3) NULL,`addr` longtext,`work` longtext)

新增数据项：

 
//新增数据项 
    var Age uint = 18 
    for i := 0; i < 5; i++ {
        time.Sleep(time.Second * 2)
        _ = db.Create(&User{Name: fmt.Sprintf("小杨%d", i), Age: Age, Birthday: time.Now()})
        Age++
    }

我们可以看到:

 
2022/06/23 10:35:28 /Users/feng/go/src/GormStart/ch03/main.go:73
[6.255ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨0',18,'2022-06-23 10:35:28.267','','')
 
2022/06/23 10:35:30 /Users/feng/go/src/GormStart/ch03/main.go:73
[4.036ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨1',19,'2022-06-23 10:35:30.275','','')
 
2022/06/23 10:35:32 /Users/feng/go/src/GormStart/ch03/main.go:73
[5.979ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨2',20,'2022-06-23 10:35:32.284','','')
 
2022/06/23 10:35:34 /Users/feng/go/src/GormStart/ch03/main.go:73
[4.307ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨3',21,'2022-06-23 10:35:34.292','','')
 
2022/06/23 10:35:36 /Users/feng/go/src/GormStart/ch03/main.go:73
[3.353ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨4',22,'2022-06-23 10:35:36.296','','')
Process 97602 has exited with status 0

单值插入：

当然我们可以使用：db.create()


db.Create(&User{Name: "小李", Age: 20, Birthday: time.Now(), Addr: "北京", Work: "程序员"})

即：


[2.769ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小李',20,'2022-06-23 10:42:39.84','北京','程序员')

批量插入

现在我们修改一下表结构

 
type User struct {
    ID           uint
    Name         string
    Email        *string
    Age          uint8
    Addr         string
    Work         string
    Birthday     *time.Time
    MemberNumber sql.NullString
    ActivatedAt  sql.NullTime
    CreatedAt    time.Time
    UpdatedAt    time.Time
}

将原来的users表删除

然后建立表：

 
//建立表
    _ = db.AutoMigrate(&User{})
//批量插入数据 
    var users = []User{{Name: "小杨"}, {Name: "小张"}, {Name: "小李"}, {Name: "小冯"}}
    db.Create(&users)
    for _, u := range users {
        fmt.Println(u.Name)
    }

输出结果：

 
[2.378ms] [rows:4] INSERT INTO `users` (`name`,`email`,`age`,`addr`,`work`,`birthday`,`member_number`,`activated_at`,`created_at`,`updated_at`) VALUES ('小杨',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小张',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小李',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小冯',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088')
小杨
小张
小李
小冯

我们还可以这样做：

 
db.Model(&User{}).Create(map[string]interface{}{
        "Name": "小刚", "Age": 25, "Addr": "广州",
    })

查找数据(R)

按排序找找

升序

 
//检索单个数据，升序
    var user User
    _ = db.First(&user)
    fmt.Println(user)

输出：

 
[1.218ms] [rows:1] SELECT * FROM `users` ORDER BY `users`.`id` LIMIT 1
{1 小杨 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

降序

 
//降序
    var user User
    _ = db.Last(&user)
    fmt.Println(user)

按照位置查找

 
//按数据表中的位置
    var user User
    _ = db.Take(&user, 2)
    fmt.Println(user)

输出：

 
[1.653ms] [rows:1] SELECT * FROM `users` WHERE `users`.`id` = 2 LIMIT 1
{2 小张 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

按照主键查找

 
    //通过主键查询
    var user User
    result := db.First(&user, 3)
    if errors.Is(result.Error, gorm.ErrRecordNotFound) {
        fmt.Println("数据未找到")
    }
    fmt.Println(user)

查找表中所有数据

 
//检索全部对象 
    var users []User
    result := db.Find(&users)
    for _, user := range users {
        fmt.Println(user)
    }
    fmt.Println(result.RowsAffected)

输出：

 
[1.553ms] [rows:5] SELECT * FROM `users`
{1 小杨 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
{2 小张 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
{3 小李 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
{4 小冯 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
{5 小刚 <nil> 25 广州  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 0001-01-01 00:00:00 +0000 UTC 0001-01-01 00:00:00 +0000 UTC}
5

根据条件查找

匹配一条数据：First()

这里db.Where().First()只会匹配一条数据

 
//根据条件检索 
    var users []User
    //匹配一条数据
    db.Where("name= ?", "小杨").First(&users)
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[2.400ms] [rows:1] SELECT * FROM `users` WHERE name= '小杨' ORDER BY `users`.`id` LIMIT 1
{1 小杨 <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

匹配多条数据：Find()

 
    db.Where("Addr = ?", "北京").Find((&users))
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[2.133ms] [rows:2] SELECT * FROM `users` WHERE Addr = '北京'
{6 小熊 <nil> 0 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:30:17.018 +0800 CST 2022-06-23 11:30:17.018 +0800 CST}
{8 小张 <nil> 0 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:33:21.414 +0800 CST 2022-06-23 11:33:21.414 +0800 CST}

注意：当我们不知道sql表中字段名的时候可以直接使用结构体，这样可以直接屏蔽数据表底层逻辑，这样我们就可以不用关心数据表的结构了

例如：

 
//此方法可屏蔽底层SQL数据表字段 
    var user User
    db.Where(&User{Name: "小杨"}).First(&user)
    fmt.Println(user)

根据条件IN检索

 
//根据条件检索 IN 
//查找age等于18、19、20的数据 
    var users []User
    db.Where("age IN ?", []uint{18, 19, 20}).Find(&users)
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[0.917ms] [rows:3] SELECT * FROM `users` WHERE age IN (18,19,20)
{9 小周 <nil> 18 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.759 +0800 CST 2022-06-23 11:49:05.759 +0800 CST}
{10 小周 <nil> 19 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.763 +0800 CST 2022-06-23 11:49:05.763 +0800 CST}
{11 小周 <nil> 20 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.77 +0800 CST 2022-06-23 11:49:05.77 +0800 CST}

根据条件AND检索

 
//根据条件检索 AND
//查找地址在北京并且大于等于18岁的人 
    var users []User
    db.Where("addr=? AND age>=?", "北京", 18).Find(&users)
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[2.181ms] [rows:3] SELECT * FROM `users` WHERE addr='北京' AND age>=18
{12 小董 <nil> 23 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.773 +0800 CST 2022-06-23 11:49:05.773 +0800 CST}
{13 小周 <nil> 18 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.964 +0800 CST 2022-06-23 11:54:55.964 +0800 CST}
{16 小画 <nil> 23 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.973 +0800 CST 2022-06-23 11:54:55.973 +0800 CST}

根据条件OR 检索

 
var users []User
db.Where("addr=? OR age>=?", "北京", 20).Find(&users)
for _, user := range users {
    fmt.Println(user)
}

输出：

 
[1.749ms] [rows:8] SELECT * FROM `users` WHERE addr='北京' OR age>=20
{5 小刚 <nil> 25 广州  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 0001-01-01 00:00:00 +0000 UTC 0001-01-01 00:00:00 +0000 UTC}
{6 小熊 <nil> 0 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:30:17.018 +0800 CST 2022-06-23 11:30:17.018 +0800 CST}
{8 小张 <nil> 0 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:33:21.414 +0800 CST 2022-06-23 11:33:21.414 +0800 CST}
{11 小周 <nil> 20 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.77 +0800 CST 2022-06-23 11:49:05.77 +0800 CST}
{12 小董 <nil> 23 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.773 +0800 CST 2022-06-23 11:49:05.773 +0800 CST}
{13 小周 <nil> 18 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.964 +0800 CST 2022-06-23 11:54:55.964 +0800 CST}
{15 小杨 <nil> 20 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.971 +0800 CST 2022-06-23 11:54:55.971 +0800 CST}
{16 小画 <nil> 23 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.973 +0800 CST 2022-06-23 11:54:55.973 +0800 CST}

使用struct & map

 
//使用struct 
    var users []User
    db.Where(&User{Name: "小周", Age: 18, Addr: "北京"}).Find(&users)
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[2.005ms] [rows:1] SELECT * FROM `users` WHERE `users`.`name` = '小周' AND `users`.`age` = 18 AND `users`.`addr` = '北京'
{13 小周 <nil> 18 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.964 +0800 CST 2022-06-23 11:54:55.964 +0800 CST}
    //使用map 
    var users []User
    db.Where(map[string]interface{}{"name": "小周", "age": 18}).Find(&users)
    // SELECT * FROM users WHERE name = "jinzhu" AND age = 20; 
    for _, user := range users {
        fmt.Println(user)
    }

输出：

 
[4.219ms] [rows:2] SELECT * FROM `users` WHERE `age` = 18 AND `name` = '小周'
{9 小周 <nil> 18 上海  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:49:05.759 +0800 CST 2022-06-23 11:49:05.759 +0800 CST}
{13 小周 <nil> 18 北京  <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:54:55.964 +0800 CST 2022-06-23 11:54:55.964 +0800 CST}

更新数据(U)

保存所有字段

Save 会保存所有的字段，即使字段是零值

 
//通过save方法更新
    var user User
    _ = db.First(&user)
    fmt.Println(user)
 
    user.Name = "小旷"
    user.Age = 22
    user.ID = 17
    user.Addr = "深圳"
    user.Work = "go开发工程师&gis开发工程师"
    _ = db.Save(&user)
    fmt.Println(user)

输出结果：

 
[rows:1] INSERT INTO `users` (`name`,`email`,`age`,`addr`,`work`,`birthday`,`member_number`,`activated_at`,`created_at`,`updated_at`,`id`) VALUES ('小旷',NULL,22,'深圳','go开发工程师&gis开发工程师',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 13:28:10.252',17)
{17 小旷 <nil> 22 深圳 go开发工程师&gis开发工程师 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 13:28:10.252 +0800 CST}

更新指定字段

 
//通过指定字段更新
//将age等于0的更新为20
    var user User
    db.Model(&user).Where("age", 0).Update("age", 20)

输出结果:

 
[rows:7] UPDATE `users` SET `age`=20,`updated_at`='2022-06-23 13:33:50.548' WHERE `age` = 0
db.Model(&user).Where("addr", "北京").Update("work", "go开发工程师")

输出结果：


[rows:5] UPDATE `users` SET `work`='go开发工程师',`updated_at`='2022-06-23 13:38:32.69' WHERE `addr` = '北京'

删除数据(D)

删除一条记录

删除一条记录时，删除对象需要指定主键，否则会触发批量 Delete

根据主键删除

 
//根据主键删除
    var user User
    db.Delete(&user, 17)

输出：

 
[rows:1] DELETE FROM `users` WHERE `users`.`id` = 17
//使用slice 
    var user User
    db.Delete(&user, []int{18, 19, 20, 21})

输出：


[rows:0] DELETE FROM `users` WHERE `users`.`id` IN (18,19,20,21)

软删除

如果您的模型包含了一个 gorm.deletedat 字段（gorm.Model 已经包含了该字段)，它将自动获得软删除的能力！

拥有软删除能力的模型调用 Delete 时，记录不会从数据库中被真正删除。但 GORM 会将 DeletedAt 置为当前时间，并且你不能再通过普通的查询方法找到该记录。

 
    // 批量删除
    db.Where("age = ?", 20).Delete(&User{})

输出：

 
rows:8] DELETE FROM `users` WHERE age = 20
// 在查询时会忽略被软删除的记录
db.Where("age = 20").Find(&user)
fmt.Println(user)

输出：查询无果，已经被软删除了


{0  <nil> 0   <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 0001-01-01 00:00:00 +0000 UTC 0001-01-01 00:00:00 +0000 UTC}

关联

Belongs To

belongs to 会与另一个模型建立了一对一的连接。这种模型的每一个实例都“属于”另一个模型的一个实例。

例如，假如我们的应用包含 user 和 company，并且每个 user 能且只能被分配给一个 company。下面的类型就表示这种关系。注意，在 UserTest 对象中，有一个和 CompanyTest 一样的 CompanyTestID。默认情况下， CompanyTestID 被隐含地用来在 UserTest 和 CompanyTest 之间创建一个外键关系，因此必须包含在 UserTest 结构体中才能填充 CompanyTest 内部结构体

外键简单解释：一张表中的外键，该表关联的另一张表的主键，例如：UserTest的外键CompanyTestID就为CompanyTest表的主键

实例：

 
// `UserTest` 属于 `CompanyTest`，`CompanyTestID` 是外键
type UserTest struct {
  gorm.Model
  Name          string
  CompanyTestID int // CompanyTestID会默认为外键
  CompanyTest   CompanyTest  //这里必须外键名前缀一致
}
 
type CompanyTest struct {
  ID   int
  Name string
}

建表：

 
func main() {
   // 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
  dsn := "root:password@tcp(127.0.0.1:3306)/gorm_test?charset=utf8mb4&parseTime=True&loc=Local"
 
  //用于输出使用的sql语句
  newLogger := logger.New(
      log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）
  logger.Config{
         SlowThreshold:             time.Second, // 慢 SQL 阈值
  LogLevel:                  logger.Info, // 日志级别
  IgnoreRecordNotFoundError: true, // 忽略ErrRecordNotFound（记录未找到）错误
  Colorful:                  true, // 禁用彩色打印
  },
  )
   //打开mysql服务中对应的数据库
  db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
      Logger: newLogger,
  })
   if err != nil {
      panic(err)
   }
 
   err = db.AutoMigrate(&UserTest{})
   if err != nil {
      panic(err)
   }

这里需要注意，gorm会先建立CompanyTest 表然后建立UserTest

写入数据：

 
//分别插入数据，并且自动写入外键值
db.Create(&UserTest{
   Name: "ice_moss",
   CompanyTest: CompanyTest{
      Name: "腾讯",
  },
})

在插入数据的时候，也是先对关联表CompanyTest插入，然后插入UserTest

或者指定ID

 
//可指定外键
db.Create(&UserTest{
   Name: "ice_moss5",
  CompanyTest: CompanyTest{
      ID:   3,
  Name: "字节跳动",
  },
})

如下图

UserTest:

GORM学习入门

CompanyTest:

GORM学习入门

关联查询

db.Preload()

 
//多表关联查询
var User1 []UserTest
db.Preload("CompanyTest").Find(&User1)
for key, value := range User1 {
   fmt.Println(key, value)
}

db.Joins()

 
//多表关联查询
var User2 UserTest
db.Joins("CompanyTest").First(&User2)
fmt.Println(User2.Name, User2.CompanyTest.Name)

has many

has many 与另一个模型建立了一对多的连接。不同于 has one，拥有者可以有零或多个关联模型。

例如，您的应用包含 user 和 credit card 模型，且每个 user 可以有多张 credit card。

 
// User 有多张 CreditCard，UserID 是外键，多个CreditCard可以对应一个User，所以每一个CreditCard都需要有外键指向User
type User struct {
    gorm.Model
    CreditCards []CreditCard
}
 
type CreditCard struct {
    gorm.Model
    Number string
    UserID uint   //外键
}

重写外键

 
type User struct {
   gorm.Model
  CreditCards []CreditCard `gorm:"foreignKey:UserRefer"`
}
 
type CreditCard struct {
   gorm.Model
  Number    string
  UserRefer uint //外键， 每一张卡需要指向唯一用户，所以每一个CreditCard需要使用外键指向User
}

现在来插入几条记录

 
//插入数据，两条卡记录指向同一user
var user User
db.Create(&user)
db.Create(&CreditCard{
   Number:    "12",
  UserRefer: user.ID,  //CreditCard外键为User的主键
})
db.Create(&CreditCard{
   Number:    "34",
  UserRefer: user.ID,  //给外键
})

CreditCard：

GORM学习入门

User:

GORM学习入门

反向查询：

 
//使用User做反向查询
var user User
db.Preload("CreditCards").First(&user)
for _, value := range user.CreditCards {
   fmt.Println(value.Number)
}

输出：

 
[2.587ms] [rows:2] SELECT * FROM `credit_cards` WHERE `credit_cards`.`user_refer` = 1 AND `credit_cards`.`deleted_at` IS NULL
 
[5.851ms] [rows:1] SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL ORDER BY `users`.`id` LIMIT 1
12
34

Many to Many

Many to Many 会在两个 model 中添加一张连接表。

例如，您的应用包含了 user 和 language，且一个 user 可以说多种 language，多个 user 也可以说一种 language。

反向引用

 
// User 拥有并属于多种 language，`user_languages` 是连接表
type User struct {
   gorm.Model
  Languages []*Language `gorm:"many2many:user_languages;"`
}
 
type Language struct {
   gorm.Model
  Name string
  Users []*User `gorm:"many2many:user_languages;"`
}

todo

 
// User 拥有并属于多种 language，`user_languages` 是连接表
type User struct {
   gorm.Model
   Languages []Language `gorm:"many2many:user_languages;"`
}
 
type Language struct {
   gorm.Model
   Name string
}

当使用 GORM 的 AutoMigrate 为 User 创建表时，GORM 会自动创建连接表

建表：

users:

GORM学习入门

languages:

GORM学习入门

user_languages:

GORM学习入门

插入记录：

 
//写入数据
var language []Language
language = append(language, Language{Name: "golang"})
language = append(language, Language{Name: "c++"})
language = append(language, Language{Name: "java"})
db.Create(&User{
   Languages: language,
})

输出：一个执行三条sql语句，分别对三张表进行插入

 
2022/07/29 22:58:29 /Users/feng/go/src/GormStart/ch11/mian.go:52
[7.552ms] [rows:3] INSERT INTO `languages` (`created_at`,`updated_at`,`deleted_at`,`name`) VALUES ('2022-07-29 22:58:29.731','2022-07-29 22:58:29.731',NULL,'golang'),('2022-07-29 22:58:29.731','2022-07-29 22:58:29.731',NULL,'c++'),('2022-07-29 22:58:29.731','2022-07-29 22:58:29.731',NULL,'java') ON DUPLICATE KEY UPDATE `id`=`id`
 
2022/07/29 22:58:29 /Users/feng/go/src/GormStart/ch11/mian.go:52
[1.197ms] [rows:3] INSERT INTO `user_languages` (`user_id`,`language_id`) VALUES (1,1),(1,2),(1,3) ON DUPLICATE KEY UPDATE `user_id`=`user_id`
 
2022/07/29 22:58:29 /Users/feng/go/src/GormStart/ch11/mian.go:52
[16.804ms] [rows:1] INSERT INTO `users` (`created_at`,`updated_at`,`deleted_at`) VALUES ('2022-07-29 22:58:29.727','2022-07-29 22:58:29.727',NULL)

users:

GORM学习入门

languages:

GORM学习入门

user_languages:

GORM学习入门

查询：

 
var user User
db.Preload("Languages").Find(&user)
for _, value := range user.Languages {
   fmt.Println(value.Name)
}

输出：

 
[0.523ms] [rows:3] SELECT * FROM `user_languages` WHERE `user_languages`.`user_id` = 1
 
[0.641ms] [rows:3] SELECT * FROM `languages` WHERE `languages`.`id` IN (1,2,3) AND `languages`.`deleted_at` IS NULL
 
[3.467ms] [rows:1] SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL
golang
c++
java

获取数据的另一种方式：

 
var user User
db.First(&user)
var languges []Language
_ = db.Model(&user).Association("Languages").Find(&languges)
for _, value := range languges {
   fmt.Println(value.Name)
}

输出：

 
[3.020ms] [rows:1] SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL ORDER BY `users`.`id` LIMIT 1
 
[1.765ms] [rows:3] SELECT `languages`.`id`,`languages`.`created_at`,`languages`.`updated_at`,`languages`.`deleted_at`,`languages`.`name` FROM `languages` JOIN `user_languages` ON `user_languages`.`language_id` = `languages`.`id` AND `user_languages`.`user_id` = 1 WHERE `languages`.`deleted_at` IS NULL
golang
c++
java

下面来介绍一个多对多的实例：

 
// User 拥有并属于多种 language，`user_languages` 是连接表type User struct {
   Name string
  gorm.Model
  Languages []*Language `gorm:"many2many:user_languages;"`
}
 
type Language struct {
   gorm.Model
  Name  string
  Users []*User `gorm:"many2many:user_languages;"`
}

写入记录：

 
//写入数据
var language []*Language
language = append(language, &Language{Name: "golang"})
language = append(language, &Language{Name: "c++"})
language = append(language, &Language{Name: "java"})
db.Create(&User{
   Languages: language,
})
 
var user []*User
user = append(user, &User{Name: "ice_moss1"})
user = append(user, &User{Name: "ice_moss2"})
user = append(user, &User{Name: "ice_moss3"})
db.Create(&Language{
   Users: user,
})

users:

GORM学习入门

languages:

GORM学习入门

user_languages:

GORM学习入门

从关联表中我们可以很直观的看出：users中ID为1的有languages中有ID为1、2、3的与之对应，同样，languages中ID为4的有languages中有ID为2、3、4的与之对应

多表关联查询我们这样做：

 
func GetAllUsers(db *gorm.DB) ([]User, error) {
   var users []User
  err := db.Model(&User{}).Preload("Languages").Find(&users).Error
   return users, err
}
 
func GetAllLanguages(db *gorm.DB) ([]Language, error) {
   var languages []Language
  err := db.Model(&languages).Preload("Users").Find(&languages).Error
   return languages, err
}

调用：

 
users, err := GetAllUsers(db)
if err != nil {
   panic(err)
}
for _, value := range users {
   fmt.Println(value.Name)
}
 
languges, err := GetAllLanguages(db)
if err != nil {
   panic(err)
}
for _, value := range languges {
   fmt.Println(value.Name)
}

输出：

 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:109
[4.635ms] [rows:6] SELECT * FROM `user_languages` WHERE `user_languages`.`user_id` IN (1,2,3,4)
 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:109
[2.984ms] [rows:4] SELECT * FROM `languages` WHERE `languages`.`id` IN (1,2,3,4) AND `languages`.`deleted_at` IS NULL
 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:109
[54.201ms] [rows:4] SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL
 
ice_moss1
ice_moss2
ice_moss3
 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:115
[1.467ms] [rows:6] SELECT * FROM `user_languages` WHERE `user_languages`.`language_id` IN (1,2,3,4)
 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:115
[1.769ms] [rows:4] SELECT * FROM `users` WHERE `users`.`id` IN (1,2,3,4) AND `users`.`deleted_at` IS NULL
 
2022/08/02 10:08:06 /Users/feng/go/src/GormStart/ch12/mian.go:115
[4.931ms] [rows:4] SELECT * FROM `languages` WHERE `languages`.`deleted_at` IS NULL
golang
c++
java

	type User struct {
	ID uint
	Name string
	Email *string
	Age uint8
	Birthday *time.Time
	MemberNumber sql.NullString
	ActivatedAt sql.NullTime
	CreatedAt time.Time
	UpdatedAt time.Time
	}

	type User struct {
	ID string // 默认情况下，名为 `ID` 的字段会作为表的主键
	Name string
	}

	// 将 `UUID` 设为主键
	type Animal struct {
	ID int64
	UUID string `gorm:"primaryKey"`
	Name string
	Age int64
	}

	// gorm.Model 的定义
	type Model struct {
	ID uint `gorm:"primaryKey"`
	CreatedAt time.Time
	UpdatedAt time.Time
	DeletedAt gorm.DeletedAt `gorm:"index"`
	}

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

	func main() {
	// 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
	dsn := "user:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"
	//注意：pass为MySQL数据库的管理员密码，dbname为要连接的数据库
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	}

	package main

	import (
	"log"
	"os"
	"time"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
	)

	//定义表结构
	type Producttest struct {
	gorm.Model
	Name string
	Code string
	Price uint
	}

	func main() {
	// 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
	dsn := "root:Qq/2013XiaoKUang@tcp(127.0.0.1:3306)/gorm_test?charset=utf8mb4&parseTime=True&loc=Local"

	//用于输出使用的sql语句
	newLogger := logger.New(
	log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）
	logger.Config{
	SlowThreshold: time.Second, // 慢 SQL 阈值
	LogLevel: logger.Info, // 日志级别
	IgnoreRecordNotFoundError: true, // 忽略ErrRecordNotFound（记录未找到）错误
	Colorful: true, // 禁用彩色打印
	},
	)

	//打开mysql服务中对应的数据库
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
	Logger: newLogger,
	})
	if err != nil {
	panic(err)
	}

	//AutoMigrate 为给定模式运行自动迁移,建立Product类型的数据表
	err = db.AutoMigrate(&Producttest{})
	if err != nil {
	log.Fatal("建表失败", err)
	}

	// Create 新增数据
	db.Create(&Producttest{Code: "01", Name: "golang程序设计", Price: 100})
	db.Create(&Producttest{Code: "02", Name: "python入门", Price: 200})

	2022/06/23 09:31:03 /Users/feng/go/src/GormStart/ch01/main.go:51
	[16.193ms] [rows:1] INSERT INTO `producttests` (`created_at`,`updated_at`,`deleted_at`,`name`,`code`,`price`) VALUES ('2022-06-23 09:31:03.35','2022-06-23 09:31:03.35',NULL,'golang程序设计','01',100)

	2022/06/23 09:31:03 /Users/feng/go/src/GormStart/ch01/main.go:52
	[2.331ms] [rows:1] INSERT INTO `producttests` (`created_at`,`updated_at`,`deleted_at`,`name`,`code`,`price`) VALUES ('2022-06-23 09:31:03.364','2022-06-23 09:31:03.364',NULL,'python入门','02',200)
	Process 96312 has exited with status 0
	Detaching
	dlv dap (96294) exited with code: 0

	var product Producttest //需要实例化一个表结构
	db.First(&product, 2) // 根据整型主键查找
	fmt.Println(product.Name)
	db.First(&product, "code = ?", "02") // 查找 code 字段值为 D42 的记录
	fmt.Println(product)

	[3.323ms] [rows:1] SELECT * FROM `producttests` WHERE `producttests`.`id` = 2 AND `producttests`.`deleted_at` IS NULL ORDER BY `producttests`.`id` LIMIT 1
	python入门

	[1.002ms] [rows:1] SELECT * FROM `producttests` WHERE code = '02' AND `producttests`.`deleted_at` IS NULL AND `producttests`.`id` = 2 ORDER BY `producttests`.`id` LIMIT 1
	{{2 2022-06-23 09:31:03.364 +0800 CST 2022-06-23 09:31:03.364 +0800 CST {0001-01-01 00:00:00 +0000 UTC false}} python入门 02 200}

	db.Model(&Producttest{}).Where("Code = ?", "01").Update("Price", "50")
	// UPDATE users SET Price='50', updated_at='2022-06-23 10:00:23.654' WHERE Code='01';

	var product Producttest
	db.Delete(&product, 1) //删除主码为1的数据

	type User struct {
	Name string
	Age uint
	Birthday time.Time
	Addr string
	Work string
	}

	func main() {
	// 参考 https://github.com/go-sql-driver/mysql#dsn-data-source-name 获取详情
	dsn := "root:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"

	//用于输出使用的sql语句
	newLogger := logger.New(
	log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer（日志输出的目标，前缀和日志包含的内容——译者注）
	logger.Config{
	SlowThreshold: time.Second, // 慢 SQL 阈值
	LogLevel: logger.Info, // 日志级别
	IgnoreRecordNotFoundError: true, // 忽略ErrRecordNotFound（记录未找到）错误
	Colorful: true, // 禁用彩色打印
	},
	)

	//打开mysql服务中对应的数据库
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
	Logger: newLogger,
	})
	if err != nil {
	panic(err)
	}

	//建立表
	_ = db.AutoMigrate(&User{})

	//新增数据项
	var Age uint = 18
	for i := 0; i < 5; i++ {
	time.Sleep(time.Second * 2)
	_ = db.Create(&User{Name: fmt.Sprintf("小杨%d", i), Age: Age, Birthday: time.Now()})
	Age++
	}

	2022/06/23 10:35:28 /Users/feng/go/src/GormStart/ch03/main.go:73
	[6.255ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨0',18,'2022-06-23 10:35:28.267','','')

	2022/06/23 10:35:30 /Users/feng/go/src/GormStart/ch03/main.go:73
	[4.036ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨1',19,'2022-06-23 10:35:30.275','','')

	2022/06/23 10:35:32 /Users/feng/go/src/GormStart/ch03/main.go:73
	[5.979ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨2',20,'2022-06-23 10:35:32.284','','')

	2022/06/23 10:35:34 /Users/feng/go/src/GormStart/ch03/main.go:73
	[4.307ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨3',21,'2022-06-23 10:35:34.292','','')

	2022/06/23 10:35:36 /Users/feng/go/src/GormStart/ch03/main.go:73
	[3.353ms] [rows:1] INSERT INTO `users` (`name`,`age`,`birthday`,`addr`,`work`) VALUES ('小杨4',22,'2022-06-23 10:35:36.296','','')
	Process 97602 has exited with status 0

	//建立表
	_ = db.AutoMigrate(&User{})
	//批量插入数据
	var users = []User{{Name: "小杨"}, {Name: "小张"}, {Name: "小李"}, {Name: "小冯"}}
	db.Create(&users)
	for _, u := range users {
	fmt.Println(u.Name)
	}

	[2.378ms] [rows:4] INSERT INTO `users` (`name`,`email`,`age`,`addr`,`work`,`birthday`,`member_number`,`activated_at`,`created_at`,`updated_at`) VALUES ('小杨',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小张',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小李',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088'),('小冯',NULL,0,'','',NULL,NULL,NULL,'2022-06-23 10:57:56.088','2022-06-23 10:57:56.088')
	小杨
	小张
	小李
	小冯

	db.Model(&User{}).Create(map[string]interface{}{
	"Name": "小刚", "Age": 25, "Addr": "广州",
	})

	//检索单个数据，升序
	var user User
	_ = db.First(&user)
	fmt.Println(user)

文章介绍

安装

模型定义

自定义配置

使用 ID 作为主键

gorm.Model

连接数据库

建表

快速入门

新增数据

查找数据

更新数据

删除数据

新增数据(C)

单值插入：

批量插入

查找数据(R)

按排序找找

按照位置查找

按照主键查找

查找表中所有数据

根据条件查找

更新数据(U)

保存所有字段

更新指定字段

删除数据(D)

删除一条记录

根据主键删除

软删除

关联

Belongs To

关联查询

db.Preload()

db.Joins()

has many

重写外键

Many to Many

反向引用

todo

使用 `ID` 作为主键

	[1.218ms] [rows:1] SELECT * FROM `users` ORDER BY `users`.`id` LIMIT 1
	{1 小杨 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

	//按数据表中的位置
	var user User
	_ = db.Take(&user, 2)
	fmt.Println(user)

	[1.653ms] [rows:1] SELECT * FROM `users` WHERE `users`.`id` = 2 LIMIT 1
	{2 小张 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

	//通过主键查询
	var user User
	result := db.First(&user, 3)
	if errors.Is(result.Error, gorm.ErrRecordNotFound) {
	fmt.Println("数据未找到")
	}
	fmt.Println(user)

	//检索全部对象
	var users []User
	result := db.Find(&users)
	for _, user := range users {
	fmt.Println(user)
	}
	fmt.Println(result.RowsAffected)

	[1.553ms] [rows:5] SELECT * FROM `users`
	{1 小杨 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
	{2 小张 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
	{3 小李 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
	{4 小冯 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}
	{5 小刚 <nil> 25 广州 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 0001-01-01 00:00:00 +0000 UTC 0001-01-01 00:00:00 +0000 UTC}
	5

	//根据条件检索
	var users []User
	//匹配一条数据
	db.Where("name= ?", "小杨").First(&users)
	for _, user := range users {
	fmt.Println(user)
	}

	[2.400ms] [rows:1] SELECT * FROM `users` WHERE name= '小杨' ORDER BY `users`.`id` LIMIT 1
	{1 小杨 <nil> 0 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 10:57:56.088 +0800 CST 2022-06-23 10:57:56.088 +0800 CST}

	db.Where("Addr = ?", "北京").Find((&users))
	for _, user := range users {
	fmt.Println(user)
	}

	[2.133ms] [rows:2] SELECT * FROM `users` WHERE Addr = '北京'
	{6 小熊 <nil> 0 北京 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:30:17.018 +0800 CST 2022-06-23 11:30:17.018 +0800 CST}
	{8 小张 <nil> 0 北京 <nil> { false} {0001-01-01 00:00:00 +0000 UTC false} 2022-06-23 11:33:21.414 +0800 CST 2022-06-23 11:33:21.414 +0800 CST}