查询

func connQuery(db *sql.DB){
        var err    error
        var rows * sql.Rows
        var conn * sql.Conn
        var val1   int = 10
        ctx, cancel := context.WithTimeout(context.Background(), 55*time.Second)
        defer cancel()
        //从连接池中返回一个连接
        conn, err    = db.Conn(ctx)
        getError(err)
        //将连接返回到连接池中
        defer conn.Close()
        rows, err = conn.QueryContext(ctx, "select col2 from testcase1 where col1 = :val",
                                                                  val1)
        getError(err)
        defer rows.Close()
        for rows.Next() {
                var val2 string
                rows.Scan(&val2)
                fmt.Println(val2)
        }
}