C#打开SqlServer的demo

        /// <summary>
        /// 判断连接对象的状态并打开连接对象
        /// </summary>
        /// <param name="con"></param>
        /// <returns></returns>
        public SqlConnection ConOpen(SqlConnection con)
        {
            switch (con.State)
            {
                case ConnectionState.Broken:
                    con.Close(); //先正常关闭，释放资源
                    con.Open();
                    break;
                case ConnectionState.Closed:
                    con.Open();
                    break;
                case ConnectionState.Connecting:
                    break;
                case ConnectionState.Executing:
                    break;
                case ConnectionState.Fetching:
                    break;
                case ConnectionState.Open:
                    break;
                default:
                    break;
            }
            return con;
        }