<add name="SQLConnString1" connectionString="server=(local);database=EpgInfo;user id=sa;password=sa;integrated security=SSPI;min pool size=4;max pool size=4;" providerName="System.Data.SqlClient"/>

------解决方案--------------------

数据库连接及访问常用几个对象和方法
class DataConn    {
       #region  建立数据库连接
       /// <summary>
       /// 建立数据库连接.
       /// </summary>
       /// <returns>返回SqlConnection对象</returns>
       public SqlConnection getcon()
       {
           string M_str_sqlcon = "Data Source=MIAMI;Initial Catalog=db_crm;Integrated Security=SSPI;";
           SqlConnection myCon = new SqlConnection(M_str_sqlcon);
           return myCon;
       }
       #endregion

       #region  执行SqlCommand命令
       /// <summary>
       /// 执行SqlCommand
       /// </summary>
       /// <param name="M_str_sqlstr">SQL语句</param>
       public void getcom(string M_str_sqlstr)
       {
           SqlConnection sqlcon = this.getcon();
           sqlcon.Open();
           SqlCommand sqlcom = new SqlCommand(M_str_sqlstr, sqlcon);
           sqlcom.ExecuteNonQuery();
           sqlcom.Dispose();
           sqlcon.Close();
           sqlcon.Dispose();
       }
       #endregion

       #region  创建DataSet对象
       /// <summary>
       /// 创建一个DataSet对象
       /// </summary>
       /// <param name="M_str_sqlstr">SQL语句</param>
       /// <param name="M_str_table">表名</param>
       /// <returns>返回DataSet对象</returns>
       public DataSet getds(string M_str_sqlstr, string M_str_table)
       {
           SqlConnection sqlcon = this.getcon();
           SqlDataAdapter sqlda = new SqlDataAdapter(M_str_sqlstr, sqlcon);
           DataSet myds = new DataSet();
           sqlda.Fill(myds, M_str_table);
           return myds;
       }
       #endregion

       #region  创建SqlDataReader对象
       /// <summary>
       /// 创建一个SqlDataReader对象
       /// </summary>
       /// <param name="M_str_sqlstr">SQL语句</param>
       /// <returns>返回SqlDataReader对象</returns>
       public SqlDataReader getread(string M_str_sqlstr)
       {
           SqlConnection sqlcon = this.getcon();
           SqlCommand sqlcom = new SqlCommand(M_str_sqlstr, sqlcon);
           sqlcon.Open();
           SqlDataReader sqlread = sqlcom.ExecuteReader(CommandBehavior.CloseConnection);
           return sqlread;
       }
       #endregion
   }
用这个类的实例的方法来实现各种sql操作就可以啦

举例，登录按钮：
private void btnLogin_Click(object sender, EventArgs e)
       {
           SqlDataReader sqlread = boperate.getread("select UserName,UserPwd from tb_User where UserName='" + cboxUName.Text.Trim() + "' and UserPwd='" + txtPwd.Text.Trim() + "'");
           sqlread.Read();
           if (sqlread.HasRows)
           {
               M_str_name = cboxUName.Text;
               M_str_pwd = txtPwd.Text.Trim();
               frmMain fmain = new frmMain();
              this.Hide();