GO -操作mysql

数据库的连接

func initmysql() (err error) {dsn := "root:0806@tcp(127.0.0.1:3306)/sql_demo" //固定格式db, err = sql.Open("mysql", dsn)if err != nil {panic(err)}err = db.Ping()if err != nil {fmt.Println("ping 失败")return err}// 数值需要根据业务情况 决定db.SetConnMaxLifetime(time.Second * 10) //10sdb.SetMaxOpenConns(3)                   //最大连接数db.SetMaxIdleConns(1)                   //复用的         //最大空闲连接数return}

主函数检测是否合法

err := initmysql()
if err != nil {fmt.Println("连接mysql失败")
}
//做完错误检查之后，确保db不为nil
defer db.Close()
fmt.Println("连接数据库mysql") //不能保证连接成功

增删查改函数

type user struct {id   intname stringage  int
} //用来接收扫描的对象func querymultirow() {sqlstr := "select * from user where id>?"rows, err := db.Query(sqlstr, 0)if err != nil {fmt.Println("queur faild", err)return}defer rows.Close()for rows.Next() {var u usererr := rows.Scan(&u.id, &u.name, &u.age)if err != nil {fmt.Println("scan faild", err)}fmt.Println(u)}} //查询多行
func queryRowdemo() {sqlstr := "select * from user where id=?"var u user//此时这个row 没有调用scan ，那么链接不会释放//记住query调用完之后，一定调用scan方法row := db.QueryRow(sqlstr, 1) //每个row 是占用连接的// 连接没有了，不能再查询了  ，程序阻塞住了row = db.QueryRow(sqlstr, 2)err := row.Scan(&u.id, &u.name, &u.age)if err != nil {fmt.Println("scan err:", err)return}fmt.Printf("id:%d name:%s age:%d\n", u.id, u.name, u.age)} //查询单行记录
func insertrowdemo() {sqlstr := "insert into user(name,age) values(?,?)"ret, err := db.Exec(sqlstr, "王五", 88)if err != nil {fmt.Println("insert err:", err)}theid, err := ret.LastInsertId() //新插入的idif err != nil {fmt.Println("insert err:", err)return}fmt.Println("insert id:", theid)} //插入数据
func updaterowdemo() {sqlstr := "update user set age=? where id=?"ret, err := db.Exec(sqlstr, 39, 1) //把id为if err != nil {fmt.Println("update err:", err)}n, err := ret.RowsAffected() //影响的行数if err != nil {fmt.Println("update err:", err)}fmt.Println("affected:", n)
} //更新数据

事务

func transactiondemo() {tx, err := db.Begin() //开启事务if err != nil {if tx != nil {tx.Rollback() //回滚}fmt.Println("begin err:", err)return}sqlstr := "update user set age=36 where id=?"ret1, err := tx.Exec(sqlstr, 1)if err != nil {tx.Rollback()fmt.Println("exec err:", err)return}aff1, err := ret1.RowsAffected()if err != nil {tx.Rollback()fmt.Println("RowsAffected", err)return}sqlstr2 := "update user set age=40 where id=?"ret2, err := tx.Exec(sqlstr2, 2)if err != nil {tx.Rollback()fmt.Println("exec err:", err)return}aff2, err := ret2.RowsAffected()if err != nil {tx.Rollback()fmt.Println("RowsAffected", err)return}fmt.Println(aff1, aff2)if aff1 == 1 && aff2 == 1 {err = tx.Commit()fmt.Println("事务提交啦")if err != nil {tx.Rollback()fmt.Println("commit err:", err)return}} else {err = tx.Rollback()fmt.Println("tx.rollback err:回滚啦", err)}}

main函数

func main() {err := initmysql()if err != nil {fmt.Println("连接mysql失败")}//做完错误检查之后，确保db不为nildefer db.Close()fmt.Println("连接数据库mysql") //不能保证连接成功查询单行数据//queryRowdemo()查询多行数据//querymultirow()插入一条数据//insertrowdemo()//updaterowdemo()querymultirow()fmt.Println("查询结束了。。。。")transactiondemo()querymultirow()
}