SQL OUTPUT存储过程不与ExecuteReader一起使用
在SQL 2008和C＃4.0上使用存储过程时，我无法检索OUTPUT信息并从Select语句返回信息。 我不断得到“对象引用未设置为对象的实例”。 当我执行ExecuteScalar（）时，我获取行，但不是数据。 在那里找到了几个例子，它们看起来像我正在做的事情，所以我想我在我面前缺少一些简单的东西。 谢谢。
存储过程
USE [PhoneDb] GO /****** Object: StoredProcedure [dbo].[TestPagingProcedure] Script Date: 06/16/2011 08:39:03 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[TestPagingProcedure] -- Add the parameters for the stored procedure here @startRowIndex int, @maximumRows int, @totalRows int OUTPUT AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; DECLARE @first_id UNIQUEIDENTIFIER DECLARE @startRow int SET @startRowIndex = (@startRowIndex - 1) * @maximumRows IF @startRowIndex = 0 SET @startRowIndex = 1 SET ROWCOUNT @startRowIndex SELECT @first_id = ExtensionGUID FROM ExtItem ORDER BY ExtensionGUID PRINT @first_id SET ROWCOUNT @maximumRows SELECT ExtensionGUID, AesExt, AesHashPassword, ToNumber, AgentExt, Name, JpgImageName, BigImageName, WbmpImageName FROM ExtItem WHERE ExtensionGUID >= @first_id ORDER BY ExtensionGUID SET ROWCOUNT 0 -- GEt the total rows SELECT @totalRows = COUNT(ExtensionGUID) FROM ExtItem END C＃代码
public bool GetPagedResults(string startRowIndex, string maxRows, ref double totalRowsReturned) { bool IsSuccess = false; string clearPassword = ""; Log.WriteLine("GetExtList : ENTERED GETEXTITEM: ", Log.DEBUG_LEVEL.VERBOSE); SqlConnection MyConnection = null; EnDecrypt hasher = null; try { if (SQLLookup.DatabaseString == "") { Log.WriteLine("GetPagedResults : SQLLookup.DatabaseString is empty:", Log.DEBUG_LEVEL.VERBOSE); SQLLookup.SQLFinder(); Log.WriteLine("GetPagedResults : SQL FINDER RUN: SQLLookup.DatabaseString:'" + SQLLookup.DatabaseString + "'", Log.DEBUG_LEVEL.VERBOSE); } Log.WriteLine("GetPagedResults: SQL Server '" + SQLLookup.DatabaseString + "'", Log.DEBUG_LEVEL.VERBOSE); _extItemList.Clear(); // Keep new records from just being appended to existing list. hasher = new EnDecrypt("SetMyKey", "SaltGenerator"); // Create a Connection to SQL Server MyConnection = new SqlConnection(@"Data Source= " + SQLLookup.DatabaseString + @"; Initial Catalog=PhoneDb;Integrated Security=True"); SqlCommand myCommand = new SqlCommand("TestPagingProcedure", MyConnection); myCommand.CommandType = CommandType.StoredProcedure; /* ASSIGN PARAMETERS */ myCommand.Parameters.Add(new SqlParameter("@startRowIndex", startRowIndex)); myCommand.Parameters.Add(new SqlParameter("@maximumRows", maxRows)); myCommand.Parameters.Add("@totalRows", SqlDbType.Int, 4); myCommand.Parameters["@totalRows"].Direction = ParameterDirection.Output; Log.WriteLine("GetPagedResults:3 After try ", Log.DEBUG_LEVEL.VERBOSE); Log.WriteLine("GetPagedResults:3 startRowIndex = " + startRowIndex + " maxRows = " + maxRows, Log.DEBUG_LEVEL.VERBOSE); MyConnection.Open(); SqlDataReader Reader = myCommand.ExecuteReader(); Log.WriteLine("GetPagedResults BEFORE WHILE LOOP", Log.DEBUG_LEVEL.VERBOSE); while (Reader.Read()) { /* BUILD EXT ITEM*/ ExtItem extItem = new ExtItem(); if (Reader.IsDBNull(0) || Reader.GetGuid(0) == Guid.Empty) extItem.ExtensionGUID = Guid.Empty; else extItem.ExtensionGUID = Reader.GetGuid(0); if (Reader.IsDBNull(1) || Reader.GetString(1) == "") extItem.AesExt = "No value"; else extItem.AesExt = Reader.GetString(1); /* ADD ITEM TO LIST */ AddItem(extItem); //Log.WriteLine("GetExtList extItem: " + extItem.ToString(), Log.DEBUG_LEVEL.VERBOSE); } // get the total rows Log.WriteLine("GetPagedResults: New Total number of pages: " + (int)myCommand.Parameters[2].Value, Log.DEBUG_LEVEL.TERSE); // totalRowsReturned = myCommand.Parameters["@totalRows"]; IsSuccess = true; MyConnection.Close(); Log.WriteLine("GetPagedResults: RETURNING:", Log.DEBUG_LEVEL.VERBOSE); } catch (Exception ex) { Log.WriteLine("GetPagedResults: Unable to retrieve Extension list. Caught Exception " + ex.Message, Log.DEBUG_LEVEL.TERSE); IsSuccess = false; } MyConnection.Close(); return IsSuccess; }
根据http://msdn.microsoft.com/en-us/library/ms971497 ，您必须在处理输出参数之前关闭datareader。