Go语言数据库编程GORM 的基本使用详解

go get -u gorm.io/gorm
go get -u gorm.io/driver/mysql
# PostgreSQL 用户：
# go get -u gorm.io/driver/postgres

package main
import (
    "gorm.io/driver/mysql"
    "gorm.io/gorm"
    "log"
)
func main() {
    dsn := "user:password@tcp(127.0.0.1:3306)/gormdb?charset=utf8mb4&parseTime=True&loc=Local"
    db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
    if err != nil {
        log.Fatal("连接数据库失败:", err)
    }
    log.Println("连接成功")
}

type User struct {
    ID       uint   `gorm:"primaryKey"`
    Name     string
    Email    string `gorm:"uniqueIndex"`
    Age      int
    CreatedAt time.Time
}

db.AutoMigrate(&User{})

user := User{Name: "Alice", Email: "alice@example.com", Age: 25}
db.Create(&user)
fmt.Println("新ID:", user.ID)

var user User
db.First(&user, 1)                         // 主键查询
db.First(&user, "email = ?", "alice@example.com") // 条件查询

var users []User
db.Where("age > ?", 20).Order("age desc").Limit(10).Find(&users)

db.Model(&user).Update("Name", "Alice Updated")
db.Model(&user).Updates(User{Name: "NewName", Age: 28}) // 多字段

db.Delete(&user)

db.Where("name LIKE ?", "%alice%").Find(&users)
db.Where("age BETWEEN ? AND ?", 20, 30).Find(&users)
db.Not("name = ?", "Bob").Find(&users)

func (u *User) BeforeCreate(tx *gorm.DB) (err error) {
    u.Name = "【新建】" + u.Name
    return
}

err := db.Transaction(func(tx *gorm.DB) error {
    if err := tx.Create(&User{Name: "TxUser"}).Error; err != nil {
        return err
    }
    if err := tx.Delete(&User{}, 1).Error; err != nil {
        return err
    }
    return nil
})

import "gorm.io/gorm/logger"
db, _ := gorm.Open(mysql.Open(dsn), &gorm.Config{
    Logger: logger.Default.LogMode(logger.Info),
})