go使用sqlx

基本使用

連接數據庫

package main

import (
	"fmt"
	"github.com/jmoiron/sqlx"
)
import _ "github.com/go-sql-driver/mysql" // 匿名導入，只會執行mysql包中的init()方法，可以不用在main中使用mysql包

var db *sqlx.DB

func initDB() (err error) {
	// DSN:Data Source Name
	dsn := "tianbao:Tianbao0913@tcp(130.179.105.87:3306)/blog_service?charset=utf8mb4&parseTime=True"
	// 也可以使用MustConnect連接不成功就panic
	db, err = sqlx.Connect("mysql", dsn)
	if err != nil {
		fmt.Printf("connect DB failed, err:%v\n", err)
		return
	}
	db.SetMaxOpenConns(200)
	db.SetMaxIdleConns(100)
	return
}

func main() {
	err := initDB() // 調用輸出化數據庫的函數
	if err != nil {
		fmt.Printf("init db failed,err:%v\n", err)
		return
	}
	fmt.Printf("init db success,\n")
}

查詢

查詢單條

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

// 查詢單條數據示例
func queryRowDemo() {
	sqlStr := "select id, name, age from user where id=?"
	var u user
	err := db.Get(&u, sqlStr, 2)
	if err != nil {
		fmt.Printf("get failed, err:%v\n", err)
		return
	}
	fmt.Printf("id:%d name:%s age:%d\n", u.ID, u.Name, u.Age)
}

查詢多條

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

// 查詢多條數據示例
func queryMultiRowDemo() {
	sqlStr := "select id, name, age from user where id > ?"
	var users []user
	err := db.Select(&users, sqlStr, 0)
	if err != nil {
		fmt.Printf("query failed, err:%v\n", err)
		return
	}
	fmt.Printf("users:%#v\n", users)
}

插入

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

// 插入數據
func insertRowDemo() {
	sqlStr := "insert into user(name, age) values (?,?)"
	ret, err := db.Exec(sqlStr, "Alex", 24)
	if err != nil {
		fmt.Printf("insert failed, err:%v\n", err)
		return
	}
	theID, err := ret.LastInsertId() // 新插入數據的id
	if err != nil {
		fmt.Printf("get lastinsert ID failed, err:%v\n", err)
		return
	}
	fmt.Printf("insert success, the id is %d.\n", theID)
}

更新

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

// 更新數據
func updateRowDemo() {
	sqlStr := "update user set age=? where id = ?"
	ret, err := db.Exec(sqlStr, 20, 2)
	if err != nil {
		fmt.Printf("update failed, err:%v\n", err)
		return
	}
	n, err := ret.RowsAffected() // 操作影響的行數
	if err != nil {
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return
	}
	fmt.Printf("update success, affected rows:%d\n", n)
}

刪除

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

// 刪除數據
func deleteRowDemo() {
	sqlStr := "delete from user where id = ?"
	ret, err := db.Exec(sqlStr, 3)
	if err != nil {
		fmt.Printf("delete failed, err:%v\n", err)
		return
	}
	n, err := ret.RowsAffected() // 操作影響的行數
	if err != nil {
		fmt.Printf("get RowsAffected failed, err:%v\n", err)
		return
	}
	fmt.Printf("delete success, affected rows:%d\n", n)
}

sqlx的NamedExec

傳參可使用key-value的形式，不用原來一個問號?對應一個參數
用來綁定SQL語句與結構體或map中的同名字段

type user struct {
	ID   int    `db:"id"`
	Age  int    `db:"age"`
	Name string `db:"name"`
}

func insertUserDemo()(err error){
	sqlStr := "INSERT INTO user (name,age) VALUES (:name,:age)"
	_, err = db.NamedExec(sqlStr,
		map[string]interface{}{
			"name": "guo",
			"age": 26,
		})
	return
}

sqlx的NamedQuery

支持查詢

func namedQuery(){
	sqlStr := "SELECT * FROM user WHERE name=:name"
	// 使用map做命名查詢
	rows, err := db.NamedQuery(sqlStr, map[string]interface{}{"name": "guo"})
	if err != nil {
		fmt.Printf("db.NamedQuery failed, err:%v\n", err)
		return
	}
	defer rows.Close()
	for rows.Next(){
		var u user
		err := rows.StructScan(&u)
		if err != nil {
			fmt.Printf("scan failed, err:%v\n", err)
			continue
		}
		fmt.Printf("user:%#v\n", u)
	}

	u := user{
		Name: "guo",
	}
	// 使用結構體命名查詢，根據結構體字段的 db tag進行映射
	rows, err = db.NamedQuery(sqlStr, u)
	if err != nil {
		fmt.Printf("db.NamedQuery failed, err:%v\n", err)
		return
	}
	defer rows.Close()
	for rows.Next(){
		var u user
		err := rows.StructScan(&u)
		if err != nil {
			fmt.Printf("scan failed, err:%v\n", err)
			continue
		}
		fmt.Printf("user:%#v\n", u)
	}
}

sqlx的事務回滾

sqlx提供了db.Beginx()和tx.Exec()方法進行事務操作

func transactionDemo2()(err error) {
	tx, err := db.Beginx() // 開啟事務
	if err != nil {
		fmt.Printf("begin trans failed, err:%v\n", err)
		return err
	}
	defer func() {
		if p := recover(); p != nil {
			tx.Rollback()
			panic(p) // re-throw panic after Rollback
		} else if err != nil {
			fmt.Println("rollback")
			tx.Rollback() // err is non-nil; don't change it
		} else {
			err = tx.Commit() // err is nil; if Commit returns error update err
			fmt.Println("commit")
		}
	}()

	sqlStr1 := "Update user set age=22 where id=?"

	rs, err := tx.Exec(sqlStr1, 1)
	if err!= nil{
		return err
	}
	n, err := rs.RowsAffected()
	if err != nil {
		return err
	}
	if n != 1 {
		return errors.New("exec sqlStr1 failed")
	}
	sqlStr2 := "Update user set age=30 where id=?"
	rs, err = tx.Exec(sqlStr2, 6)
	if err!=nil{
		return err
	}
	n, err = rs.RowsAffected()
	if err != nil {
		return err
	}
	if n != 1 {
		return errors.New("exec sqlStr1 failed")
	}
	return err
}