瞎忙了一阵, 没有什么成果,,, 真是郁闷呀

我努力地啃着书本知识, 可以是还是没有什么成功, 在网上东拉西凑的,还是没有成功
那我再努力吧

using System;
using System.Data;
using System.Data.SqlClient;

namespace DemoBIMS
{
    /**//// <summary>
    /// Summary description for SqlTools.
    /// </summary>
    public class SqlTools
    {
        public SqlTools()
        {
            //
            // TODO: Add constructor logic here
            //
        }
        private SqlConnection _sqlConn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["strConn"]);
        private SqlConnection _sqlNVS=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["strNVS"]);
        private DataSet tmpDS=null;
        public DataSet GetData(string strSQL)
        {
            SqlDataAdapter _sqlDA=new SqlDataAdapter(strSQL,_sqlConn);
            this.tmpDS=new DataSet();
            try
            {
                _sqlDA.Fill(this.tmpDS,"_tmp");
                return tmpDS;
            }
            catch(Exception)
            {
                return null;
            }
            finally
            {
                _sqlDA.Dispose();
                this._sqlConn.Close();
            }
        }
        public void Update2Source(DataSet ds,string strSelCMD)
        {
            SqlDataAdapter _sqlDA=new SqlDataAdapter();
            _sqlDA.SelectCommand=new SqlCommand(strSelCMD,this._sqlConn);
            SqlCommandBuilder cb=new SqlCommandBuilder(_sqlDA);
            try
            {
                _sqlDA.Update(ds,"_tmp");
                ds.AcceptChanges();
            }
            catch(Exception)
            {
                //
            }
            finally
            {
            _sqlDA.Dispose();
            this._sqlConn.Close();
            }
        }
    
        public int SqlExecuteNonQuery(string strSQL)
        {
            SqlCommand _sqlCMD=new SqlCommand(strSQL,this._sqlConn);
            this._sqlConn.Open();
            try
            {
                return _sqlCMD.ExecuteNonQuery();
            }
            catch(Exception)
            {
                this._sqlConn.Close();
                return 0;
            }
            finally
            {
                _sqlCMD.Dispose();
                this._sqlConn.Close();
            }
        }
        public int GetDataReader(string strSQL)
        {
            SqlCommand _sqlCMD=this._sqlConn.CreateCommand();
            _sqlCMD.CommandText=strSQL;
            try
            {
                this._sqlConn.Open();
                return (int) _sqlCMD.ExecuteScalar();
            }
            catch(Exception)
            {
                this._sqlConn.Close();
                _sqlCMD.Dispose();
                return 0;
            }
            finally
            {
                this._sqlConn.Close();
                _sqlCMD.Dispose();
            }
            
        }
        public bool CheckDataSetIsNull(System.Data.DataSet ds)
        {
            if (ds==null)
                return true;
            else
                return false;
        }
        public string [] SplitDouble(double d)
        {
            string _tmpStr=d.ToString();
            string [] _Str=_tmpStr.Split(char.Parse("."));
        //    uint int16=Convert.ToInt16(_Str[0]);
            return _Str;
        }
        public DataSet GetDetailSMNUM(int SMNUM)
        {
            string strSQL="SELECT * FROM DNOTE WHERE SMNUM=@SMNUM";
            SqlDataAdapter _sqlDA=new SqlDataAdapter();
            _sqlDA.SelectCommand=new SqlCommand(strSQL,this._sqlNVS);
//            _sqlDA.SelectCommand.CommandType=CommandType.Text;
            _sqlDA.SelectCommand.Parameters.Add("@SMNUM",SqlDbType.Int,4,"SMNUM");
            _sqlDA.SelectCommand.Parameters["@SMNUM"].Value=SMNUM;
            
            //_sqlDA.SelectCommand.Connection=this._sqlNVS;
            this.tmpDS=new DataSet();
            try
            {
                _sqlDA.Fill(this.tmpDS,"_tmp");
                return tmpDS;
            }
            catch(Exception)
            {
                return null;
            }
            finally
            {
                this._sqlConn.Close();
                _sqlDA.Dispose();
            }
        }
    }
}