GORM中文文档
读者可以直接看文档，本文只是从文档记录个人常用的一些操作。

1.安装

package main

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

type Product struct {
    gorm.Model //嵌入常用字段
    Code string
    Price uint
}

func main() {
    db, err := gorm.Open("mysql", "root:@(localhost:3306)/golang_mysql")
    if err != nil {
        panic("failed to connect database")
    }
    //关闭数据库连接
    defer db.Close()

    //创建表
    db.AutoMigrate(&Product{})

    // 插入
    db.Create(&Product{Code: "L1212", Price: 1000})

    // 读取
    var product Product
    db.First(&product, 1) // 查询id为1的product
    db.First(&product, "code = ?", "L1212") // 查询code为l1212的product

    // 更新
    db.Model(&product).Update("Price", 2000)

    // 删除
    db.Delete(&product)
}

2.1 增

• demo

type Animal struct {
    ID   int64
    Name string `gorm:"default:'galeone'"`
    Age  int64
}

生成的 SQL 语句会排除没有值或值为 零值 的字段。 将记录插入到数据库后，Gorm会从数据库加载那些字段的值。注意 所有字段的零值, 比如 0, '', false 或者其它 零值，都不会保存到数据库内，但会使用他们的默认值。

2.2 删

！！！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。

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%";

• 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

// Unscoped 方法可以物理删除记录
db.Unscoped().Delete(&order)
//// DELETE FROM orders WHERE id=10;

2.3 查

// 获取第一条匹配的记录
db.Where("name = ?", "jinzhu").First(&user)
//// SELECT * FROM users WHERE name = 'jinzhu' limit 1;

// 获取全部匹配的记录
db.Where("name = ?", "jinzhu").Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu';

// <>
db.Where("name <> ?", "jinzhu").Find(&users)

// IN
db.Where("name IN (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)

// LIKE
db.Where("name LIKE ?", "%jin%").Find(&users)

// AND
db.Where("name = ? AND age >= ?", "jinzhu", "22").Find(&users)

// 时间
db.Where("updated_at > ?", lastWeek).Find(&users)

// BETWEEN
db.Where("created_at BETWEEN ? AND ?", lastWeek, today).Find(&users)

2.AND (Struct & Map)

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";

4.Or 条件

db.Where("amount > ?", DB.Table("orders").Select("AVG(amount)").Where("state = ?", "paid").QueryExpr()).Find(&orders)
// SELECT * FROM "orders"  WHERE "orders"."deleted_at" IS NULL AND
// (amount > (SELECT AVG(amount) FROM "orders"  WHERE (state = 'paid')));

2.选择字段

db.Order("age desc, name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;

// 多字段排序
db.Order("age desc").Order("name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;

// 覆盖排序
db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
//// SELECT * FROM users ORDER BY age desc; (users1)
//// SELECT * FROM users ORDER BY age; (users2)

4.数量

db.Offset(3).Find(&users)
//// SELECT * FROM users OFFSET 3;

// -1 取消 Offset 条件
db.Offset(10).Find(&users1).Offset(-1).Find(&users2)
//// SELECT * FROM users OFFSET 10; (users1)
//// SELECT * FROM users; (users2)

6.总数

rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Rows()
for rows.Next() {
    ...
}
rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Rows()
for rows.Next() {
    ...
}
type Result struct {
    Date  time.Time
    Total int64
}
db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Scan(&results)

7.连接

var ages []int64
db.Find(&users).Pluck("age", &ages)

var names []string
db.Model(&User{}).Pluck("name", &names)

db.Table("deleted_users").Pluck("name", &names)

// 想查询多个字段？ 这样做：
db.Select("name, age").Find(&users)

9.扫描
Scan，扫描结果至一个 struct.

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;

• 更新修改字段

// 开启事务
tx := db.Begin()

// 在事务中执行具体的数据库操作 (事务内的操作使用 'tx' 执行，而不是 'db')
tx.Create(...)

// ...

// 如果发生错误则执行回滚
tx.Rollback()

// 或者（未发生错误时）提交事务
tx.Commit()

一个例子

db.Exec("DROP TABLE users;")
db.Exec("UPDATE orders SET shipped_at=? WHERE id IN (?)", time.Now(), []int64{11,22,33})

// Scan
type Result struct {
    Name string
    Age  int
}

var result Result
db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result)

• sql.Row 和 sql.Rows
  通过 *sql.Row 或 *sql.Rows 获取查询结果

rows, err := db.Model(&User{}).Where("name = ?", "jinzhu").Select("name, age, email").Rows() // (*sql.Rows, error)
defer rows.Close()

for rows.Next() {
  var user User
  // ScanRows 扫描一行记录到 user
  db.ScanRows(rows, &user)

  // do something
}