sqlhelper.cs

网上购物系统源代码加毕业设计论文

		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{
			using (SqlConnection cn = new SqlConnection(connectionString))
			{
				cn.Open();

				//调用重载方法
				return ExecuteDataset(cn, commandType, commandText, commandParameters);
			}
		}



		/// <summary>
		/// Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="connection">a valid SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType, string commandText)
		{
			return ExecuteDataset(connection, commandType, commandText, (SqlParameter[])null);
		}
		
		/// <summary>
		/// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{
			//创建一个SqlCommand对象，并对其进行初始化
			SqlCommand cmd = new SqlCommand();
			PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);
			
			//创建SqlDataAdapter对象以及DataSet
			SqlDataAdapter da = new SqlDataAdapter(cmd);
			DataSet ds = new DataSet();

			//填充ds
			da.Fill(ds);
			
			// 清除cmd的参数集合	
			cmd.Parameters.Clear();
			
			//返回ds
			return ds;						
		}
		



		/// <summary>
		/// Execute a SqlCommand that returns the first column of the first record against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
		public static object ExecuteScalar(string connString, CommandType cmdType, string cmdText, params SqlParameter[] cmdParms) 
		{
			SqlCommand cmd = new SqlCommand();

			using (SqlConnection conn = new SqlConnection(connString)) 
			{
				PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms);
				object val = cmd.ExecuteScalar();
				cmd.Parameters.Clear();
				return val;
			}
		}

		/// <summary>
		/// Execute a SqlCommand that returns the first column of the first record against an existing database connection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		/// </remarks>
		/// <param name="conn">an existing database connection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
		public static object ExecuteScalar(SqlConnection conn, CommandType cmdType, string cmdText, params SqlParameter[] cmdParms) 
		{
			
			SqlCommand cmd = new SqlCommand();

			PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms);
			object val = cmd.ExecuteScalar();
			cmd.Parameters.Clear();
			return val;
		}

		/// <summary>
		/// add parameter array to the cache
		/// </summary>
		/// <param name="cacheKey">Key to the parameter cache</param>
		/// <param name="cmdParms">an array of SqlParamters to be cached</param>
		public static void CacheParameters(string cacheKey, params SqlParameter[] cmdParms) 
		{
			parmCache[cacheKey] = cmdParms;
		}

		/// <summary>
		/// Retrieve cached parameters
		/// </summary>
		/// <param name="cacheKey">key used to lookup parameters</param>
		/// <returns>Cached SqlParamters array</returns>
		public static SqlParameter[] GetCachedParameters(string cacheKey) 
		{
			SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];
			
			if (cachedParms == null)
				return null;
			
			SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];

			for (int i = 0, j = cachedParms.Length; i < j; i++)
				clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

			return clonedParms;
		}

		/// <summary>
		/// Prepare a command for execution
		/// </summary>
		/// <param name="cmd">SqlCommand object</param>
		/// <param name="conn">SqlConnection object</param>
		/// <param name="trans">SqlTransaction object</param>
		/// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
		/// <param name="cmdText">Command text, e.g. Select * from Products</param>
		/// <param name="cmdParms">SqlParameters to use in the command</param>
		private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms) 
		{
			//判断连接的状态。如果是关闭状态，则打开
			if (conn.State != ConnectionState.Open)
				conn.Open();
			//cmd属性赋值
			cmd.Connection = conn;
			cmd.CommandText = cmdText;
			//是否需要用到事务处理
			if (trans != null)
				cmd.Transaction = trans;
				
			cmd.CommandType = cmdType;
			//添加cmd需要的存储过程参数
			if (cmdParms != null) 
			{
				foreach (SqlParameter parm in cmdParms)
					cmd.Parameters.Add(parm);
			}
		}
	}
}