sqlhelper.cs

比较好的异步数据库访问示例

		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbConnection connection, CommandType commandType, string commandText)
		{
			//pass through the call providing null for the set of IDataParameters
			return ExecuteScalar(connection, commandType, commandText, (SqlParameter[])null);
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="connection">a valid IDbConnection</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 IDataParameters used to execute the command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbConnection connection, CommandType commandType, string commandText, params IDataParameter[] commandParameters)
		{
			return ExecuteScalar(connection, (SqlTransaction)null, commandType, commandText, commandParameters);
		}

		/// <summary>
		/// Execute a stored procedure via a command (that returns a 1x1 resultset) against the specified IDbConnection 
		/// 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>
		/// <param name="connection">a valid IDbConnection</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>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbConnection 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)) 
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				SqlParameter[] commandParameters = (SqlParameter[])SqlHelperParameterCache.GetSpParameterSet(connection.ConnectionString, spName);

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

				//call the overload that takes an array of IDataParameters
				return ExecuteScalar(connection, CommandType.StoredProcedure, spName, commandParameters);
			}
				//otherwise we can just call the SP without params
			else 
			{
				return ExecuteScalar(connection, CommandType.StoredProcedure, spName);
			}
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="transaction">a valid IDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbTransaction transaction, CommandType commandType, string commandText)
		{
			//pass through the call providing null for the set of IDataParameters
			return ExecuteScalar(transaction, commandType, commandText, (SqlParameter[])null);
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="transaction">a valid IDbTransaction</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 IDataParameters used to execute the command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbTransaction transaction, CommandType commandType, string commandText, params IDataParameter[] commandParameters)
		{
			return ExecuteScalar(transaction.Connection, transaction, commandType, commandText, commandParameters);
		}

		/// <summary>
		/// Execute a stored procedure via a command (that returns a 1x1 resultset) against the specified
		/// IDbTransaction 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>
		/// <param name="transaction">a valid IDbTransaction</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>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar(IDbTransaction transaction, 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 = (SqlParameter[])SqlHelperParameterCache.GetSpParameterSet(transaction.Connection.ConnectionString, spName);

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

				//call the overload that takes an array of IDataParameters
				return ExecuteScalar(transaction, CommandType.StoredProcedure, spName, commandParameters);
			}
				//otherwise we can just call the SP without params
			else 
			{
				return ExecuteScalar(transaction, CommandType.StoredProcedure, spName);
			}
		}

		private delegate object ExecuteScalarDelegate1(string connectionString, CommandType commandType, string commandText);
		private delegate object ExecuteScalarDelegate2(string connectionString, CommandType commandType, string commandText, params IDataParameter[] commandParameters);
		private delegate object ExecuteScalarDelegate3(string connectionString, string spName, params object[] parameterValues);
		private delegate object ExecuteScalarDelegate4(IDbConnection connection, CommandType commandType, string commandText);
		private delegate object ExecuteScalarDelegate5(IDbConnection connection, CommandType commandType, string commandText, params IDataParameter[] commandParameters);
		private delegate object ExecuteScalarDelegate6(IDbConnection connection, string spName, params object[] parameterValues);
		private delegate object ExecuteScalarDelegate7(IDbTransaction transaction, CommandType commandType, string commandText);
		private delegate object ExecuteScalarDelegate8(IDbTransaction transaction, CommandType commandType, string commandText, params IDataParameter[] commandParameters);
		private delegate object ExecuteScalarDelegate9(IDbTransaction transaction, string spName, params object[] parameterValues);

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="connectionString">a valid connection string for a IDbConnection yet to be opened</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="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(string connectionString, CommandType commandType, string commandText, AsyncCallback ac, Object state)
		{
			ExecuteScalarDelegate1 d = new ExecuteScalarDelegate1(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connectionString, commandType, commandText, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="connectionString">a valid connection string for a IDbConnection yet to be opened</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="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <param name="commandParameters">an array of IDataParameters used to execute the command</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(string connectionString, CommandType commandType, string commandText, AsyncCallback ac, Object state, params IDataParameter[] commandParameters)
		{
			ExecuteScalarDelegate2 d = new ExecuteScalarDelegate2(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connectionString, commandType, commandText, commandParameters, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a stored procedure via a command (that returns a 1x1 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>
		/// <param name="connectionString">a valid connection string for a IDbConnection</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(string connectionString, string spName, AsyncCallback ac, Object state, params object[] parameterValues)
		{
			ExecuteScalarDelegate3 d = new ExecuteScalarDelegate3(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connectionString, spName, parameterValues, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="connection">a valid IDbConnection</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="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(IDbConnection connection, CommandType commandType, string commandText, AsyncCallback ac, Object state)
		{
			ExecuteScalarDelegate4 d = new ExecuteScalarDelegate4(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connection, commandType, commandText, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="connection">a valid IDbConnection</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="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <param name="commandParameters">an array of IDataParameters used to execute the command</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(IDbConnection connection, CommandType commandType, string commandText, AsyncCallback ac, Object state, params IDataParameter[] commandParameters)
		{
			ExecuteScalarDelegate5 d = new ExecuteScalarDelegate5(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connection, commandType, commandText, commandParameters, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a stored procedure via a command (that returns a 1x1 resultset) against the specified IDbConnection 
		/// 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>
		/// <param name="connection">a valid IDbConnection</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(IDbConnection connection, string spName, AsyncCallback ac, Object state, params object[] parameterValues)
		{
			ExecuteScalarDelegate6 d = new ExecuteScalarDelegate6(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(connection, spName, parameterValues, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>
		/// <param name="transaction">a valid IDbTransaction</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="ac">callback object containing a delegate</param>
		/// <param name="state">state object supplied by the client</param>
		/// <returns>asynchronous result object</returns>
		public static IAsyncResult BeginExecuteScalar
			(IDbTransaction transaction, CommandType commandType, string commandText, AsyncCallback ac, Object state)
		{
			ExecuteScalarDelegate7 d = new ExecuteScalarDelegate7(ExecuteScalar);
			IAsyncResult result = d.BeginInvoke(transaction, commandType, commandText, ac, state);
			return result;
		}

		/// <summary>
		/// Execute a command (that returns a 1x1 resultset) using the provided parameters.
		/// </summary>