1. Order
1.1 简单使用
age字段降序,name字段升序(默认)
db.Order("age desc, name").Find(&users)
SELECT * FROM users ORDER BY age desc, name;
或者写成
db.Order("age desc").Order("name").Find(&users)
- 示例
package main
import (
"fmt"
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/mysql"
)
type xiShu struct {
ID int64
Name string
Age int64
}
func(xiShu) TableName() string {
return "xi_shu"
}
func main() {
db,_ := connect()
defer db.Close()
var users []xiShu
//var user xiShu
result := db.Order("age desc, name").Find(&users)
fmt.Println(result.Value)
}
func connect() (db *gorm.DB,err error) {
db, err = gorm.Open("mysql", "root:40010355@tcp(127.0.0.1:3306)/crow?charset=utf8&parseTime=True&loc=Local")
if err != nil {
fmt.Printf(err.Error())
defer db.Close()
}else {
fmt.Printf("OK\n")
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)
//defer db.Close()
}
return
}
输出
OK
&[{1 LiuBei 28} {2 GuanYu 22} {6 MaChao 20} {3 ZhangFei 20} {5 ZhuGeLiang 20} {4 ZhaoYun 18}]
1.2 重新排序
同一个表作两个排序,分别保存到结构体切片
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)
- 示例
上例中,main函数替换为如下内容:
func main() {
db,_ := connect()
defer db.Close()
var users1,users2 []xiShu
//var user xiShu
//result := db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
//fmt.Println(result.Value)
fmt.Println(users1,"\n",users2)
}
2. Limit
db.Limit(3).Find(&users)
SELECT * FROM users LIMIT 3;
// 用 -1 取消 LIMIT 限制条件
db.Limit(10).Find(&users1).Limit(-1).Find(&users2)
SELECT * FROM users LIMIT 10; (users1)
SELECT * FROM users; (users2)
3. Offset
跳过前三行,取两行。
db.Limit(2).Offset(3).Find(&users)
输出
OK
[{4 ZhaoYun 18} {5 ZhuGeLiang 20}]
- 用 -1 取消 OFFSET 限制条件(同Limit)
4. Count
func main() {
db,_ := connect()
defer db.Close()
var users []xiShu
var count int64
db.Where("age = ?",20).Find(&users).Count(&count)
fmt.Println(users,count)
}
输出为:
OK
[{3 ZhangFei 20} {5 ZhuGeLiang 20} {6 MaChao 20}] 3
5. Pluck
将表格中的age列单独取出作为一个集合
- 示例(数字列)
func main() {
db,_ := connect()
defer db.Close()
var users []xiShu
var ages []int64
db.Find(&users).Pluck("age", &ages)
fmt.Println(ages)
}
输出
OK
[28 22 20 18 20 20]
- 示例(字串列)
func main() {
db,_ := connect()
defer db.Close()
//var users []xiShu
//var user xiShu
var names []string
//db.Model(&xiShu{}).Pluck("name", &names)
db.Find(&[]xiShu{}).Pluck("name", &names)
fmt.Println(names)
//fmt.Println(users)
}
也可以写成
db.Table("xi_shu").Pluck("name", &names)
输出为
OK
[LiuBei GuanYu ZhangFei ZhaoYun ZhuGeLiang MaChao]
6. Scan
func main() {
db,_ := connect()
defer db.Close()
type Result struct {
Name string
Age int
}
var result Result
db.Table("xi_shu").Select("name, age").Where("name = ?", "LiuBei").Scan(&result)
fmt.Println(result)
}
输出结果
OK
{LiuBei 28}