gorm系列-简单入门

简介

GORM系列：b站搜七米

文档：https://www.liwenzhou.com/posts/Go/gorm/

什么是ORM：Object(对象) Relational(关系) Mapping(映射)

对象：程序中的对象/实例 例如Go中的结构体实例

关系：关系数据库 例如MySQL

gorm的官方文档：https://gorm.io/zh_CN/docs/

案例

举个不用gorm的例子

type UserInfo struct {
    ID uint
    Name string
    Gender string
    Hobby string
}

func main()  {
    u1 := UserInfo{1, "zisefeizhu", "男","篮球"}
    //将u1数据存入数据库
    insert into userinfo values(1, "紫色飞猪","男","篮球");  //sql语句
}

要求开发不仅会go还要熟练掌握sql语句

使用gorm的例子

type UserInfo struct {
    ID uint
    Name string
    Gender string
    Hobby string
}

func main()  {
    u1 := UserInfo{1, "zisefeizhu", "男","篮球"}
    //将u1数据存入数据库
    orm.Create(&u1)   //orm语句不要太简单  
}

ORM优缺点

优点：提高开发效率

缺点：牺牲执行性能、牺牲灵活性、弱化SQL能力

入门

安装gorm

E:\gostudent\gin\lesson19>go get -u github.com/jinzhu/gorm

**安装mysql ** 下载地址：https://dev.mysql.com/downloads/mysql/

1、 解压到指定目录， 例如：E:\mysql
2、 管理员cmd到bin目录 例如：E:\mysql\mysql-8.0.19-winx64\bin
3、 执行： mysqld –initialize –console 记下密码：-YML?i2uo7gz(密码随机生成，每次密码不一样，如果没记住，删掉data文件夹，重新执行该命令）
4、 创建mysql8服务：mysqld –install mysql8
5、 启动mysql8：net start mysql8
6、 登陆修改密码

    e:\mysql\mysql-8.0.19-winx64\bin>mysql -uroot -p
    Enter password: ************
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 8
    Server version: 8.0.19

    Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

    Oracle is a registered trademark of Oracle Corporation and/or its
    affiliates. Other names may be trademarks of their respective
    owners.

    Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

    mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';
    Query OK, 0 rows affected (0.22 sec)

    mysql> flush privileges;
    Query OK, 0 rows affected (0.06 sec)
    mysql> exit
    Bye
    e:\mysql\mysql-8.0.19-winx64\bin>mysql -uroot -p
    Enter password: 123456

7、 windows环境变量设置

8、 SQLyog连接

    mysql> ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';  #修改加密规则
    mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456'; #修改密码加密策略
    Query OK, 0 rows affected (0.06 sec)

    mysql> flush privileges;  #刷新权限
    Query OK, 0 rows affected (0.04 sec)

GORM基本示例

使用SQLyog Professional 64 学习

package main

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

//UserInfo -->数据表
type UserInfo struct {
    ID int
    Name string
    Gender string
    Hobby string
}
func main() {
    //连接MySQL数据库
    //方法1
    //connArgs := fmt.Sprintf("%s:%s@%s(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local", "root","123456", "tcp","127.0.0.1", 3306, "db" )
    //db, err := gorm.Open("mysql", connArgs)
    //方法2    一定要细心啊
    db, err := gorm.Open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parseTime=True&loc=Local")
    //panic: dial tcp [::1]:3306: connectex: No connection could be made because the target machine actively refused it. 数据库没打开 被拒绝

    if err != nil{
        panic(err)
    }
    defer db.Close()

    //创建表 自动迁移(把结构体和数据表进行对应)
    db.AutoMigrate(&UserInfo{})

    //创建数据行
    u1 := UserInfo{3, "紫色飞猪","男","直播"}
    db.Create(&u1)
}

简单的增删改查

package main

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

//UserInfo -->数据表
type UserInfo struct {
    ID int
    Name string
    Gender string
    Hobby string
}
func main() {
    //连接MySQL数据库
    //方法1
    //connArgs := fmt.Sprintf("%s:%s@%s(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local", "root","123456", "tcp","127.0.0.1", 3306, "db" )
    //db, err := gorm.Open("mysql", connArgs)
    //方法2    一定要细心啊
    db, err := gorm.Open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parseTime=True&loc=Local")
    //panic: dial tcp [::1]:3306: connectex: No connection could be made because the target machine actively refused it. 数据库没打开 被拒绝

    if err != nil{
        panic(err)
    }
    defer db.Close()

    //创建表 自动迁移(把结构体和数据表进行对应)
    db.AutoMigrate(&UserInfo{})

    ////创建数据行
    //u1 := UserInfo{3, "紫色飞猪","男","直播"}
    //db.Create(&u1)

    //查询
    var u UserInfo
    db.First(&u)   //查询一行
    fmt.Printf("u:%#v\n",u)
    var u1 UserInfo
    db.Last(&u1)   //查询最后一行
    fmt.Printf("u1:%#v\n",u1)
    //更新
    db.Model(&u).Update("hobby","双色球")
    //删除
    db.Delete(&u).Delete("")
}

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