三层架构之数据库访问层完全篇(C#)

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

namespace DbBase
{

 public abstract class Base
 {

  #region "Fields of base calss"

  protected static string strConn = ConfigurationSettings.AppSettings["strConnection"];

  protected static string strSQL;

  #endregion
  

  #region "Properties of base class"
    }

  #endregion

  #region "Functions of base class"
  public Base()
  {
   //
   // TODO: Add constructor logic here
   //
  }

  /// <summary>
  /// executing SQL commands
  /// </summary>
  /// <param name="strSQL">string</param>
  /// <returns>return int</returns>
  protected static int ExecuteSql(string strSQL)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   SqlCommand myCmd = new SqlCommand(strSQL,myCn);
   try
   {
    myCn.Open();
    myCmd.ExecuteNonQuery();
    return 0;
   }
   catch(System.Data.SqlClient.SqlException e)
   {    
    throw new Exception(e.Message);
   }
   finally
   {
    myCmd.Dispose();
    myCn.Close();
   }
  }

  /// <summary>
  ///executing SQL commands
  /// </summary>
  /// <param name="strSQL">要执行的SQL语句,为字符串类型string</param>
  /// <returns>返回执行情况,整形int</returns>
  protected static int ExecuteSqlEx(string strSQL)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   SqlCommand myCmd = new SqlCommand(strSQL,myCn);
   
   try
   {
    myCn.Open();    
    SqlDataReader myReader = myCmd.ExecuteReader();
    if(myReader.Read())
    {
     return 0;
    } 
    else
    {
     throw new Exception("Value Unavailable!");
    }
   }
   catch(System.Data.SqlClient.SqlException e)
   {        
    throw new Exception(e.Message);
   }
   finally
   {
    myCmd.Dispose();
    myCn.Close();
   }
  }

  /// <summary>
  /// get dataset
  /// </summary>
  /// <param name="strSQL">(string)</param>
  /// <returns>(DataSet)</returns>
  protected static DataSet ExecuteSql4Ds(string strSQL)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   try
   {
    myCn.Open();
    SqlDataAdapter sda = new SqlDataAdapter(strSQL,myCn);
    DataSet ds = new DataSet("ds");
    sda.Fill(ds);
    return ds;
   }
   catch(System.Data.SqlClient.SqlException e)
   {    
    throw new Exception(e.Message);
   }
   finally
   {
    myCn.Close();
   }
  }

  /// <summary>
  /// get single value
  /// </summary>
  /// <param name="strSQL">(string)</param>
  /// <returns>(int)</returns>
  protected static int ExecuteSql4Value(string strSQL)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   SqlCommand myCmd = new SqlCommand(strSQL,myCn);
   try
   {
    myCn.Open();
    object r = myCmd.ExecuteScalar();
    if(Object.Equals(r,null))
    {
     throw new Exception("value unavailable！");
    }
    else
    {
     return (int)r;
    }    
   }
   catch(System.Data.SqlClient.SqlException e)
   {    
    throw new Exception(e.Message);
   }
   finally
   {
    myCmd.Dispose();
    myCn.Close();
   }
  }  

  /// <summary>
  /// get object
  /// </summary>
  /// <param name="strSQL">(string)</param>
  /// <returns>(object)</returns>
  protected static object ExecuteSql4ValueEx(string strSQL)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   SqlCommand myCmd = new SqlCommand(strSQL,myCn);
   try
   {
    myCn.Open();
    object r = myCmd.ExecuteScalar();
    if(Object.Equals(r,null))
    {
     throw new Exception("object unavailable!");
    }
    else
    {
     return r;
    }    
   }
   catch(System.Data.SqlClient.SqlException e)
   {    
    throw new Exception(e.Message);
   }
   finally
   {
    myCmd.Dispose();
    myCn.Close();
   }
  }

  /// <summary>
  /// execute multipul SQL commands
  /// </summary>
  /// <param name="strSQLs">string</param>
  /// <returns>int</returns>
  protected static int ExecuteSqls(string[] strSQLs)
  {
   SqlConnection myCn = new SqlConnection(strConn);   
   SqlCommand myCmd = new SqlCommand();   
   int j=strSQLs.Length;

   try
   {
    myCn.Open();    
   }
   catch(System.Data.SqlClient.SqlException e)
   {
    throw new Exception(e.Message);
   }
   SqlTransaction myTrans = myCn.BeginTransaction();

   try
   {           
    myCmd.Connection = myCn;    
    myCmd.Transaction = myTrans;

    foreach(string str in strSQLs)
    {
     myCmd.CommandText = str;
     myCmd.ExecuteNonQuery();
    }
    myTrans.Commit();
    return 0;
   }
   catch(System.Data.SqlClient.SqlException e)
   {   
    myTrans.Rollback();
    throw new Exception(e.Message);
   }
   finally
   {
    myCmd.Dispose();
    myCn.Close();
   }
  }

  #endregion
 }
}

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