sqlhelper.cs

这个是网上相册系统的一个架构设计说明

				// assign the provided values to these parameters based on parameter order 
				AssignParameterValues(commandParameters, parameterValues);

				// call the overload that takes an array of SqlParameters 
				return  ExecuteDataset(transaction, CommandType.StoredProcedure, spName, commandParameters);
			} 
				// otherwise we can just call the SP without params 
			else  
			{
				return  ExecuteDataset(transaction, CommandType.StoredProcedure, spName);
			} 
		} 
 
		#endregion  ExecuteDataSet 
        
		#region  ExecuteReader 
 
		/**/ ///   <summary> 
		///  this enum is used to indicate whether the connection was provided by the caller, or created by SqlHelper, so that
		///  we can set the appropriate CommandBehavior when calling ExecuteReader()
		///   </summary> 
		private   enum  SqlConnectionOwnership    
		{
			/**/ ///   <summary> Connection is owned and managed by SqlHelper </summary> 
			Internal, 
			/**/ ///   <summary> Connection is owned and managed by the caller </summary> 
			External
		} 
 
		/**/ ///   <summary> 
		///  Create and prepare a SqlCommand, and call ExecuteReader with the appropriate CommandBehavior.
		///   </summary> 
		///   <remarks> 
		///  If we created and opened the connection, we want the connection to be closed when the DataReader is closed.
		///  
		///  If the caller provided the connection, we want to leave it to them to manage.
		///   </remarks> 
		///   <param name="connection"> a valid SqlConnection, on which to execute this command </param> 
		///   <param name="transaction"> a valid SqlTransaction, or 'null' </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 SqlParameters to be associated with the command or 'null' if no parameters are required </param> 
		///   <param name="connectionOwnership"> indicates whether the connection parameter was provided by the caller, or created by SqlHelper </param> 
		///   <returns> SqlDataReader containing the results of the command </returns> 
		private   static  SqlDataReader ExecuteReader(SqlConnection connection, SqlTransaction transaction, CommandType commandType,  string  commandText, SqlParameter[] commandParameters, SqlConnectionOwnership connectionOwnership)
		{    
			// create a command and prepare it for execution 
			SqlCommand cmd  =   new  SqlCommand();
			PrepareCommand(cmd, connection, transaction, commandType, commandText, commandParameters);
            
			// create a reader 
			SqlDataReader dr;

			//  call ExecuteReader with the appropriate CommandBehavior 
			if  (connectionOwnership  ==  SqlConnectionOwnership.External)
			{
				dr  =  cmd.ExecuteReader();
			} 
			else 
			{
				dr  =  cmd.ExecuteReader(CommandBehavior.CloseConnection);
			} 
            
			//  detach the SqlParameters from the command object, so they can be used again. 
			cmd.Parameters.Clear();
            
			return  dr;
		} 
 
		/**/ ///   <summary> 
		///  Execute a SqlCommand (that returns a resultset and takes no parameters) against the database specified in 
		///  the connection string. 
		///   </summary> 
		///   <remarks> 
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders");
		///   </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> 
		///   <returns> a SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader( string  connectionString, CommandType commandType,  string  commandText)
		{
			// pass through the call providing null for the set of SqlParameters 
			return  ExecuteReader(connectionString, commandType, commandText, (SqlParameter[]) null );
		} 
 
		/**/ ///   <summary> 
		///  Execute a SqlCommand (that returns a resultset) against the database specified in the connection string 
		///  using the provided parameters.
		///   </summary> 
		///   <remarks> 
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders", 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> a SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader( string  connectionString, CommandType commandType,  string  commandText,  params  SqlParameter[] commandParameters)
		{
			// create & open a SqlConnection 
			SqlConnection cn  =   new  SqlConnection(connectionString);
			cn.Open();

			try 
			{
				// call the private overload that takes an internally owned connection in place of the connection string 
				return  ExecuteReader(cn,  null , commandType, commandText, commandParameters,SqlConnectionOwnership.Internal);
			} 
			catch 
			{
				// if we fail to return the SqlDatReader, we need to close the connection ourselves 
				cn.Close();
				throw ;
			} 
		} 
 
		/**/ ///   <summary> 
		///  Execute a stored procedure via a SqlCommand (that returns a resultset) against the database specified in 
		///  the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
		///  stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		///   </summary> 
		///   <remarks> 
		///  This method provides no access to output parameters or the stored procedure's return value parameter.
		///  
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(connString, "GetOrders", 24, 36);
		///   </remarks> 
		///   <param name="connectionString"> a valid connection string for a SqlConnection </param> 
		///   <param name="spName"> the name of the stored procedure </param> 
		///   <param name="parameterValues"> an array of objects to be assigned as the input values of the stored procedure </param> 
		///   <returns> a SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader( string  connectionString,  string  spName,  params   object [] parameterValues)
		{
			// if we receive parameter values, we need to figure out where they go 
			if  ((parameterValues  !=   null )  &&  (parameterValues.Length  >   0 )) 
			{
				// pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache) 
				SqlParameter[] commandParameters  =  SqlHelperParameterCache.GetSpParameterSet(connectionString, spName);

				// assign the provided values to these parameters based on parameter order 
				AssignParameterValues(commandParameters, parameterValues);

				// call the overload that takes an array of SqlParameters 
				return  ExecuteReader(connectionString, CommandType.StoredProcedure, spName, commandParameters);
			} 
				// otherwise we can just call the SP without params 
			else  
			{
				return  ExecuteReader(connectionString, CommandType.StoredProcedure, spName);
			} 
		} 
 
		/**/ ///   <summary> 
		///  Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlConnection. 
		///   </summary> 
		///   <remarks> 
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(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 SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader(SqlConnection connection, CommandType commandType,  string  commandText)
		{
			// pass through the call providing null for the set of SqlParameters 
			return  ExecuteReader(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.:  
		///   SqlDataReader dr = ExecuteReader(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 SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader(SqlConnection connection, CommandType commandType,  string  commandText,  params  SqlParameter[] commandParameters)
		{
			// pass through the call to the private overload using a null transaction value and an externally owned connection 
			return  ExecuteReader(connection, (SqlTransaction) null , commandType, commandText, commandParameters, SqlConnectionOwnership.External);
		} 
 
		/**/ ///   <summary> 
		///  Execute a stored procedure via a SqlCommand (that returns a resultset) against the specified SqlConnection 
		///  using the provided parameter values.  This method will query the database to discover the parameters for the 
		///  stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		///   </summary> 
		///   <remarks> 
		///  This method provides no access to output parameters or the stored procedure's return value parameter.
		///  
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(conn, "GetOrders", 24, 36);
		///   </remarks> 
		///   <param name="connection"> a valid SqlConnection </param> 
		///   <param name="spName"> the name of the stored procedure </param> 
		///   <param name="parameterValues"> an array of objects to be assigned as the input values of the stored procedure </param> 
		///   <returns> a SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader(SqlConnection connection,  string  spName,  params   object [] parameterValues)
		{
			// if we receive parameter values, we need to figure out where they go 
			if  ((parameterValues  !=   null )  &&  (parameterValues.Length  >   0 )) 
			{
				SqlParameter[] commandParameters  =  SqlHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

				AssignParameterValues(commandParameters, parameterValues);

				return  ExecuteReader(connection, CommandType.StoredProcedure, spName, commandParameters);
			} 
				// otherwise we can just call the SP without params 
			else  
			{
				return  ExecuteReader(connection, CommandType.StoredProcedure, spName);
			} 
		} 
 
		/**/ ///   <summary> 
		///  Execute a SqlCommand (that returns a resultset and takes no parameters) against the provided SqlTransaction. 
		///   </summary> 
		///   <remarks> 
		///  e.g.:  
		///   SqlDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders");
		///   </remarks> 
		///   <param name="transaction"> a valid SqlTransaction </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 SqlDataReader containing the resultset generated by the command </returns> 
		public   static  SqlDataReader ExecuteReader(SqlTransaction transaction, CommandType commandType,  string  commandText)
		{
			// pass through the call providing null for the set of SqlParameters 
			return  ExecuteReader(transaction, commandType, commandText, (SqlParameter[]) null );
		} 
 
		/**/ ///   <summary> 
		///  Execute a SqlCommand (that returns a resultset) against the specified SqlTransaction
		///  using the provided parameters.
		///   </summary> 
		///   <remarks> 
		///  e.g.: