初学ADO.NET时写的数据库访问类[4]

  /// <summary>
  /// 执行delete，update,insert操作，返回值为受影响的行数
  /// </summary>
  public int ExeNoQuery(SqlCommand sqlCmd)
  {
   int nRet = -1;
   m_strError = "";
   sqlCmd.Connection = m_sqlCnn;
   try
   {
    OpenCnn();
    nRet = sqlCmd.ExecuteNonQuery();
   }
   catch (SqlException ex)
   {
    nRet = -1;
    m_strError = ex.ToString();
   }
   finally
   {
    if (m_sqlCnn.State==ConnectionState.Open)
    {
     m_sqlCnn.Close();
    }
   }
   return nRet;
  }

  //判断是否存在
  public int ExeIsExist(string strSql)
  {
   int nExist = -1;
   m_strError = "";
   SqlCommand sqlCmd = new SqlCommand(strSql,m_sqlCnn);
   try
   {
    OpenCnn();
    SqlDataReader sqlReader = sqlCmd.ExecuteReader();
    if (sqlReader.Read())
    {
     nExist = 1;
    }
    else
    {
     nExist = 0;
    }

   }
   catch (SqlException ex)
   {
    nExist = -1;
    m_strError = ex.ToString();
   }
   finally
   {
    if (m_sqlCnn.State==ConnectionState.Open)
    {
     sqlCmd.Dispose();
     m_sqlCnn.Close();
    }
   }
   return nExist;
  }

  /// <summary>
  /// 判断是否存在
  /// </summary>
  public int ExeIsExist(SqlCommand sqlCmd)
  {
   int nExist = -1;
   m_strError = "";
   sqlCmd.Connection = m_sqlCnn;
   try
   {
    OpenCnn();
    SqlDataReader sqlReader = sqlCmd.ExecuteReader();
    if (sqlReader.Read())
    {
     nExist = 1;
    }
    else
    {
     nExist = 0;
    }
   }
   catch (SqlException ex)
   {
    nExist = -1;
    m_strError = ex.ToString();
   }
   finally
   {
    if (m_sqlCnn.State==ConnectionState.Open)
    {
     m_sqlCnn.Close();
    }
   }
   return nExist;
  }

  /// <summary>
  /// //返回DataSet
  /// </summary>
  public DataSet ExeSqlDs(string strSql, string strTable)
  {
   m_strError = "";
   SqlDataAdapter sqlAdapter = new SqlDataAdapter(strSql,m_sqlCnn);
   DataSet dbSet = new DataSet();
   try
   {
    sqlAdapter.Fill(dbSet,strTable);
   }
   catch (SqlException ex)
   {
    dbSet = null;
    m_strError = ex.ToString();
   }
   
   return dbSet;
  }