package main

import (
	"database/sql"
	_ "github.com/go-sql-driver/mysql"
	"log"
)

var Db *sql.DB

func initdb() (err error) {
	Db, err = sql.Open("mysql", "root:123456@tcp(43.143.245.135:3306)/user")
	if err != nil {
		log.Println(err)
		return err
	}
	err = Db.Ping()
	if err != nil {
		log.Println(err)
		return err
	}
	log.Println("Successfully connected to mysql")
	Db.SetMaxOpenConns(10)
	Db.SetMaxIdleConns(5)
	return nil
}

func main() {
	err := initdb()
	if err != nil {
		return
	}
	transaction()

}

func transaction() {
	//开启事务
	tx, err := Db.Begin()
	if err != nil {
		log.Println("begin failed", err)
		return
	}
	//执行多个sql操作,即一个事务
	sqlstr1 := `update user set age=age-1 where id=1`
	sqlstr2 := `update user set age=age+1 where id=2`

	_, err = tx.Exec(sqlstr1)
	if err != nil {
		log.Println("执行sql1出错了，要回滚", err)
		//回滚操作
		tx.Rollback()
		return
	}
	_, err = tx.Exec(sqlstr2)
	if err != nil {
		log.Println("执行sql2出错了，要回滚", err)
		//回滚操作
		tx.Rollback()
		return
	}
	//上两步操作都执行成功，就提交本次事务
	err = tx.Commit()
	if err != nil {
		log.Println(err)
		return
	}
	log.Println("事务执行成功")
}