database/sql
的扩展。其特点是:把SQL执行的结果集转化成数据结构(Struct、Maps、Slices)。支持问号(?)或命名的Prepared Statements,避免SQL注入的安全问题。而xorm支持的数据库有:Mysql、MyMysql、Postgre、SQlite、Mssql ,支持事务:当使用事务处理时,需要创建Session对象 ,链式api ,支持原始SQL语句和ORM操作的混合执行
Gorm的安装
我们要想使用gorm插件,首先要会的是如何的安装,安装的前提是必须已经配置好golang环境,然后安装gorm也很简单,一条命令即可。
go get -u github.com/jinzhu/gorm
我们已经安装好了gorm,下面就是连接mysql,不过连接是需要对mysql中的表进行操作,所以我们需要创建一个方法,然后在连接,根据方法对表进行操作。
package main//包申明 import ( "fmt" "github.com/jinzhu/gorm" _ "github.com/jinzhu/gorm/dialects/mysql" ) //个人技术博客http://www.wulaoer.org type User struct { Id int Name string Data string } func main() { dsn := "root:root@tcp(127.0.0.1:3306)/test?charset=utf8mb4&parseTime=True&loc=Local" //用户名:密码@tcp(IP:端口)/数据库名?charset=utf8mb4&parseTime=True&loc=Local db, err := gorm.Open("mysql", dsn) if err != nil { fmt.Println("mysql open failed,",err) } //通过数据的指针创建表 //db.CreateTable(&User{}) //根据表结构创建表,并指定表名 db.Table("wulaoer").CreateTable(&User{}) db.Close() }
Has Table
// 检查模型User的表是否存在 db.HasTable(&User{}) // 检查表users是否存在 db.HasTable("users")
// 为模型User创建表 db.CreateTable(&User{}) // 创建表时会追加ENGINE=InnoDB到SQL语句中 db.Set("gorm:table_options", "ENGINE=InnoDB").CreateTable(&User{})
Drop Table
// 删除模型User的表 db.DropTable(&User{}) // 删除表users db.DropTable("users") // 删除模型User的表和表products db.DropTableIfExists(&User{}, "products") // 删除多张表,如果表存在则删除
删除/软删除
// 删除存在的记录 db.Delete(&email) //// DELETE from emails where id=10; // 为Delete语句添加额外的SQL选项 db.Set("gorm:delete_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Delete(&email) //// DELETE from emails where id=10 OPTION (OPTIMIZE FOR UNKNOWN);
批量删除
删除所有匹配记录
db.Where("email LIKE ?", "%jinzhu%").Delete(Email{}) //// DELETE from emails where email LIKE "%jinhu%"; db.Delete(Email{}, "email LIKE ?", "%jinzhu%") //// DELETE from emails where email LIKE "%jinhu%";
软删除
DeletedAt
字段,它将自动获得软删除功能! 那么在调用Delete
时不会从数据库中永久删除,而是只将字段DeletedAt
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; // 软删除的记录将在查询时被忽略 db.Where("age = 20").Find(&user) //// SELECT * FROM users WHERE age = 20 AND deleted_at IS NULL; // 使用Unscoped查找软删除的记录 db.Unscoped().Where("age = 20").Find(&users) //// SELECT * FROM users WHERE age = 20; // 使用Unscoped永久删除记录 db.Unscoped().Delete(&order) //// DELETE FROM orders WHERE id=10;
insert table
// 默认表名插入数据 db.Create(&User{Id: 1,Name: "wolf",Data: "ssss"}) // 自定义表名插入数据 db.Table("wulaoer").Create(&User{Id: 1,Name: "wolf",Data: "wulaoer"})
Add Indexes
// 为name列添加名为idx_user_name的普通索引 db.Model(&User{}).AddIndex("idx_user_name", "name") // 为name和age两列添加名为idx_user_name_age的复合索引 db.Model(&User{}).AddIndex("idx_user_name_age", "name", "age") // 添加唯一索引 db.Model(&User{}).AddUniqueIndex("idx_user_name", "name") // 为多列添加唯一索引 db.Model(&User{}).AddUniqueIndex("idx_user_name_age", "name", "age")
Remove Index
// 删除索引 db.Model(&User{}).RemoveIndex("idx_user_name")
数据库配置
var DB *gorm.DB func main() { //获得一个*grom.DB对象 DB, err := gorm.Open("mysql", "username:password@/database?charset=utf8&parseTime=True&loc=Local") if err != nil { fmt.Println("Gorm 异常:", err) } //根据*grom.DB对象获得*sql.DB的通用数据库接口 sqlDb := DB.DB() defer sqlDb.Close() database := GetConfig() fmt.Println("maxConn: ", database.MaxConn) fmt.Println("maxOpen: ", database.MaxOpen) sqlDb.SetMaxIdleConns(database.MaxConn) //设置最大连接数 sqlDb.SetMaxOpenConns(database.MaxOpen) //设置最大的空闲连接数 data, _ := json.Marshal(sqlDb.Stats()) //获得当前的SQL配置情况 fmt.Println(string(data)) }
普通查询
// 根据主键查询第一条记录 db.First(&user) SELECT * FROM users ORDER BY id LIMIT 1; // 随机获取一条记录 db.Take(&user) SELECT * FROM users LIMIT 1; // 根据主键查询最后一条记录 db.Last(&user) SELECT * FROM users ORDER BY id DESC LIMIT 1; // 查询所有的记录 db.Find(&users) SELECT * FROM users; // 查询指定的某条记录(仅当主键为整型时可用) db.First(&user, 10) SELECT * FROM users WHERE id = 10;
where查询
// Get first matched record db.Where("name = ?", "jinzhu").First(&user) SELECT * FROM users WHERE name = 'jinzhu' limit 1; // Get all matched records db.Where("name = ?", "jinzhu").Find(&users) SELECT * FROM users WHERE name = 'jinzhu'; // <> db.Where("name <> ?", "jinzhu").Find(&users) SELECT * FROM users WHERE name <> 'jinzhu'; // IN db.Where("name IN (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users) SELECT * FROM users WHERE name in ('jinzhu','jinzhu 2'); // LIKE db.Where("name LIKE ?", "%jin%").Find(&users) SELECT * FROM users WHERE name LIKE '%jin%'; // AND db.Where("name = ? AND age >= ?", "jinzhu", "22").Find(&users) SELECT * FROM users WHERE name = 'jinzhu' AND age >= 22; // Time db.Where("updated_at > ?", lastWeek).Find(&users) SELECT * FROM users WHERE updated_at > '2000-01-01 00:00:00'; // BETWEEN db.Where("created_at BETWEEN ? AND ?", lastWeek, today).Find(&users) SELECT * FROM users WHERE created_at BETWEEN '2000-01-01 00:00:00' AND '2000-01-08 00:00:00';
Struct & Map查询
// Struct db.Where(&User{Name: "jinzhu", Age: 20}).First(&user) SELECT * FROM users WHERE name = "jinzhu" AND age = 20 LIMIT 1; // Map db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users) SELECT * FROM users WHERE name = "jinzhu" AND age = 20; // 主键的切片 db.Where([]int64{20, 21, 22}).Find(&users) SELECT * FROM users WHERE id IN (20, 21, 22);
提示:当通过结构体进行查询时,GORM将会只通过非零值字段查询,这意味着如果你的字段值为0,‘’,false或者其他零值时,将不会被用于构建查询条件,例如:
db.Where(&User{Name: "jinzhu", Age: 0}).Find(&users) SELECT * FROM users WHERE name = "jinzhu";
Not条件查询
db.Not("name", "jinzhu").First(&user) //// SELECT * FROM users WHERE name <> "jinzhu" LIMIT 1; // Not In db.Not("name", []string{"jinzhu", "jinzhu 2"}).Find(&users) //// SELECT * FROM users WHERE name NOT IN ("jinzhu", "jinzhu 2"); // Not In slice of primary keys db.Not([]int64{1,2,3}).First(&user) //// SELECT * FROM users WHERE id NOT IN (1,2,3); db.Not([]int64{}).First(&user) //// SELECT * FROM users; // Plain SQL db.Not("name = ?", "jinzhu").First(&user) //// SELECT * FROM users WHERE NOT(name = "jinzhu"); // Struct db.Not(User{Name: "jinzhu"}).First(&user) //// SELECT * FROM users WHERE name <> "jinzhu";
注意:使用主键查询时,应仔细检查所传递的值是否为有效主键,以避免SQL注入
// 按主键获取 db.First(&user, 23) //// SELECT * FROM users WHERE id = 23 LIMIT 1; // 简单SQL db.Find(&user, "name = ?", "jinzhu") //// SELECT * FROM users WHERE name = "jinzhu"; db.Find(&users, "name <> ? AND age > ?", "jinzhu", 20) //// SELECT * FROM users WHERE name <> "jinzhu" AND age > 20; // Struct db.Find(&users, User{Age: 20}) //// SELECT * FROM users WHERE age = 20; // Map db.Find(&users, map[string]interface{}{"age": 20}) //// SELECT * FROM users WHERE age = 20;
Or条件查询
db.Where("role = ?", "admin").Or("role = ?", "super_admin").Find(&users) //// SELECT * FROM users WHERE role = 'admin' OR role = 'super_admin'; // Struct db.Where("name = 'jinzhu'").Or(User{Name: "jinzhu 2"}).Find(&users) //// SELECT * FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; // Map db.Where("name = 'jinzhu'").Or(map[string]interface{}{"name": "jinzhu 2"}).Find(&users)
查询链
Gorm有一个可链接的API,你可以这样使用它
db.Where("name <> ?","jinzhu").Where("age >= ? and role <> ?",20,"admin").Find(&users) //// SELECT * FROM users WHERE name <> 'jinzhu' AND age >= 20 AND role <> 'admin'; db.Where("role = ?", "admin").Or("role = ?", "super_admin").Not("name = ?", "jinzhu").Find(&users)
db.First(&user) user.Name = "jinzhu 2" user.Age = 100 db.Save(&user) //// UPDATE users SET name='jinzhu 2', age=100, birthday='2016-01-01', updated_at = '2013-11-17 21:34:10' WHERE id=111;
Update
,
// 更新单个属性(如果更改) db.Model(&user).Update("name", "hello") //// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111; // 使用组合条件更新单个属性 db.Model(&user).Where("active = ?", true).Update("name", "hello") //// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111 AND active=true; // 使用`map`更新多个属性,只会更新这些更改的字段 db.Model(&user).Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false}) //// UPDATE users SET name='hello', age=18, actived=false, updated_at='2013-11-17 21:34:10' WHERE id=111; // 使用`struct`更新多个属性,只会更新这些更改的和非空白字段 db.Model(&user).Updates(User{Name: "hello", Age: 18}) //// UPDATE users SET name='hello', age=18, updated_at = '2013-11-17 21:34:10' WHERE id = 111; // 警告:当使用struct更新时,FORM将仅更新具有非空值的字段 // 对于下面的更新,什么都不会更新为"",0,false是其类型的空白值 db.Model(&user).Updates(User{Name: "", Age: 0, Actived: false})
Select
,
db.Model(&user).Select("name").Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false}) //// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111; db.Model(&user).Omit("name").Updates(map[string]interface{}{"name": "hello", "age": 18, "actived": false}) //// UPDATE users SET age=18, actived=false, updated_at='2013-11-17 21:34:10' WHERE id=111;
BeforeUpdate
, AfterUpdate
方法,更新其UpdatedAt
时间戳,在更新时保存它的Associations
,如果不想调用它们,可以使用UpdateColumn
,
// 更新单个属性,类似于`Update` db.Model(&user).UpdateColumn("name", "hello") //// UPDATE users SET name='hello' WHERE id = 111; // 更新多个属性,与“更新”类似 db.Model(&user).UpdateColumns(User{Name: "hello", Age: 18}) //// UPDATE users SET name='hello', age=18 WHERE id = 111;
db.Table("users").Where("id IN (?)", []int{10, 11}).Updates(map[string]interface{}{"name": "hello", "age": 18}) //// UPDATE users SET name='hello', age=18 WHERE id IN (10, 11); // 使用struct更新仅适用于非零值,或使用map[string]interface{} db.Model(User{}).Updates(User{Name: "hello", Age: 18}) //// UPDATE users SET name='hello', age=18; // 使用`RowsAffected`获取更新记录计数 db.Model(User{}).Updates(User{Name: "hello", Age: 18}).RowsAffected
使用SQL表达式更新
DB.Model(&product).Update("price", gorm.Expr("price * ? + ?", 2, 100)) //// UPDATE "products" SET "price" = price * '2' + '100', "updated_at" = '2013-11-17 21:34:10' WHERE "id" = '2'; DB.Model(&product).Updates(map[string]interface{}{"price": gorm.Expr("price * ? + ?", 2, 100)}) //// UPDATE "products" SET "price" = price * '2' + '100', "updated_at" = '2013-11-17 21:34:10' WHERE "id" = '2'; DB.Model(&product).UpdateColumn("quantity", gorm.Expr("quantity - ?", 1)) //// UPDATE "products" SET "quantity" = quantity - 1 WHERE "id" = '2'; DB.Model(&product).Where("quantity > 1").UpdateColumn("quantity", gorm.Expr("quantity - ?", 1)) //// UPDATE "products" SET "quantity" = quantity - 1 WHERE "id" = '2' AND quantity > 1;
BeforeUpdate
, BeforeSave
更改回调中的更新值,可以使用scope.SetColumn
func (user *User) BeforeSave(scope *gorm.Scope) (err error) { if pw, err := bcrypt.GenerateFromPassword(user.Password, 0); err == nil { scope.SetColumn("EncryptedPassword", pw) } }
额外更新选项
// 为Update语句添加额外的SQL选项 db.Model(&user).Set("gorm:update_option", "OPTION (OPTIMIZE FOR UNKNOWN)").Update("name, "hello") //// UPDATE users SET name='hello', updated_at = '2013-11-17 21:34:10' WHERE id=111 OPTION (OPTIMIZE FOR UNKNOWN);
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