SQL连接类

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace DAL
{
    public class DataControl
    {
        public static string connectionString = "server=" + SystemSet.getServerSet_ServerIP() + ";uid=" + SystemSet.getServerSet_ServerUser() + ";pwd=" + SystemSet.getServerSet_ServerPass() + ";database=" + SystemSet.getServerSet_ServerDataBase() + "";
        /// <summary>
        /// 初始化        /// </summary>
        public DataControl()
        {
        }
        /// <summary>
        /// 无参数，测试数据库连接是否设置合理。        /// </summary>
        /// <returns>是否连接成功</returns>
        public static bool checkconn()
        {
            try
            {
                SqlConnection conn = new SqlConnection(connectionString);
                conn.Open();
                return true;
            }
 &