存储过程未返回值-C#

我有一个存储过程：

ALTER PROCEDURE [dbo].[DeleteFromSchoolMain]
    @TblName VARCHAR(50),
    @MainID VARCHAR(10),
    @TblCol VARCHAR(50),
    @rowsCount INT OUTPUT
AS
BEGIN
    SET NOCOUNT ON;

    DECLARE @RelTbl AS Nvarchar(50)
    DECLARE @ColForFK AS Nvarchar(50)
    DECLARE @TblMaterial AS NVARCHAR(50)
    DECLARE @ColMaterialID AS NVARCHAR(50)
    DECLARE @ColMaterialFK AS NVARCHAR(50)
    DECLARE @cmdForMaterial AS NVARCHAR(max)
    DECLARE @TblSubject AS NVARCHAR(50)
    DECLARE @ColSubjectID AS NVARCHAR(50)
    DECLARE @ColSubjectFK AS NVARCHAR(50)
    DECLARE @cmdForSubject AS NVARCHAR(max)

    Set @ColForFK = SUBSTRING(@TblCol,1, DATALENGTH(@TblCol)-2)
    Set @ColForFK = @ColForFK+'FK'

    DECLARE @cmd AS NVARCHAR(max)
    DECLARE @TempCount int

    SET @MainID = ''''+@MainID+ ''''

    SET @RelTbl = 'ClassSubMatRelation'
    --For Class Material
    SET @TblMaterial = 'ClassMaterial'
    SET @ColMaterialID = 'ClassMaterialID'
    SET @ColMaterialFK = 'ClassMaterialFK'

    SET @cmd = N'UPDATE ' + @RelTbl + ' SET Status_Info = 0 WHERE ' +  @ColForFK + ' = ' + @MainID -- Delete from ClassRelation Table
    EXEC(@cmd)
    SET @TempCount = @@ROWCOUNT
    SET @rowsCount = @TempCount + @rowsCount;

    SET @cmd = N'UPDATE ' + @TblName + ' SET Status_Info = 0 WHERE ' +  @TblCol + ' = ' + @MainID -- Delete from Main Table
    EXEC(@cmd)
    SET @TempCount = @@ROWCOUNT 
    SET @rowsCount = @TempCount + @rowsCount;

    -------------------------------------Board-----------------------------------
    IF (@TblName = 'Board')
    BEGIN

        SET @cmdForMaterial = N'UPDATE '+@TblMaterial+' Set Status_Info = 0 where '+@ColMaterialID+' in ( Select s.'+@ColMaterialFK+' from  '+@RelTbl+' s where s.' +  @ColForFK + ' = ' +  @MainID + ' AND s.ClassSubjectFK IN ( SELECT T.ClassSubjectFK FROM ' + @RelTbl + ' T WHERE  T.'+@ColForFK+' = '+ @MainID + ') and s.ClassSubjectFK NOT IN ( SELECT E.ClassSubjectFK FROM ' +@RelTbl+' E WHERE E.'+@ColForFK+' != '+ @MainID +') and s.'+@ColMaterialFK+'  is not null )'
        EXEC(@cmdForMaterial)   
        SET @TempCount = @@ROWCOUNT 
        SET @rowsCount = @TempCount + @rowsCount;
        SET @TempCount = 0;


        --For Class Subject
        SET @TblMaterial = 'ClassSubject'
        SET @ColMaterialID = 'ClassSubjectID'
        SET @ColMaterialFK = 'ClassSubjectFK'

        SET @cmdForMaterial = N'UPDATE '+@TblMaterial+' Set Status_Info = 0 where '+@ColMaterialID+' in ( Select s.'+@ColMaterialFK+' from  '+@RelTbl+' s where s.' +  @ColForFK + ' = ' +  @MainID + ' AND s.ClassSubjectFK IN ( SELECT T.ClassSubjectFK FROM ' + @RelTbl + ' T WHERE  T.'+@ColForFK+' = '+ @MainID + ') and s.ClassSubjectFK NOT IN ( SELECT E.ClassSubjectFK FROM ' +@RelTbl+' E WHERE E.'+@ColForFK+' != '+ @MainID +') and s.'+@ColMaterialFK+'  is not null )'
        EXEC(@cmdForMaterial)   
        SET @TempCount = @@ROWCOUNT 
        SET @rowsCount = @TempCount + @rowsCount;
        SET @TempCount = 0;


    END

        ------------------------------ Class Subject ------------------------------------
    ELSE IF (@TblName = 'ClassSubject')
    BEGIN                   

        SET @cmdForMaterial = N'UPDATE '+@TblMaterial+' Set '+@TblMaterial+'.Status_Info = 0 from '+@TblMaterial+' tm join '+@RelTbl+' rt on rt.'+@ColMaterialFK+' = tm.'+@ColMaterialID+' where rt.'+@ColForFK+ ' = '+ @MainID
        EXEC(@cmdForMaterial)

        SET @TempCount = @@ROWCOUNT 
        SET @rowsCount = @TempCount + @rowsCount;
        SET @TempCount = 0;
    END

END
GO

我用C#执行它，如下所示：

var rowsAffected = 0;

using (SqlConnection conn = new SqlConnection(Constants.Connection))
{
     conn.Open();

     SqlCommand cmd = new SqlCommand("DeleteFromSchoolMain", conn);
     cmd.CommandType = CommandType.StoredProcedure;

     cmd.Parameters.AddWithValue("@TblName", abundleBoard.TempName);
     cmd.Parameters.AddWithValue("@MainID", abundleBoard.MainID.ToString());
     cmd.Parameters.AddWithValue("@TblCol", abundleBoard.TblCol);

     SqlParameter outputParam = new SqlParameter();
     outputParam.ParameterName = "@rowsCount";
     outputParam.SqlDbType = System.Data.SqlDbType.Int;
     outputParam.Direction = System.Data.ParameterDirection.Output;
     cmd.Parameters.Add(outputParam);

     object o = cmd.ExecuteScalar();

     if (!outputParam.Value.Equals(DBNull.Value))
     {
         rowsAffected = Convert.ToInt32(outputParam.Value);
         string q = o.ToString();
     }

     conn.Close();
}

但我的问题是，我在输出参数中没有得到任何东西。我不理解这个问题，而且我觉得我的存储过程没有得到优化。我可以做些什么来加快查询的执行速度吗？索引和分区我已经尽了最大的努力

编辑：

在@SurjitSD和@PeterB的帮助下，我得到了一个解决方案：-

在我的程序中，我在顶部添加了一行：-

SET @rowsCount=0

在c#中，我将代码更改为：-

 cmd.ExecuteNonQuery();
 if (!cmd.Parameters["@rowsCount"].Value.Equals(DBNull.Value))
  {
   rowsAffected = Convert.ToInt32(cmd.Parameters["@rowsCount"].Value);
  }

---

现在这个很好用

您正在用c#调用

ExecuteScalar

ExecuteScalar

将为您提供过程中的

Select

语句返回的第一行和第一列值

您需要使用

ExecuteNonQuery

在

ExecuteNonQuery

之后，您可以获得如下值

cmd.Parameters["@rowsCount"].Value

如果在

设置@rowscont

之后使用

选择@rowscont

，也可以使用

ExecuteScalar

获取值。然后，您不需要在sql和c中对任何参数提及

输出方向

#

ExecuteScalar示例

Sql过程

Alter procedure SomeProcedure
(
@someVariable int
:
:
)
Begin
   /*Some processing logic of procedure*/

    Select @SomeVariable //any variable Or Value from procedure needed as output in c#
End

C#

---编辑--

在c#中没有得到值的实际原因是（附说明）

参数

@rowscont

在使用之前未初始化。的确如此

null

在执行SET

@rowscont=@TempCount+@rowscont

时，实际上是在

null

中添加了一些内容。向

null

添加任何内容都将成为

null

---

所以

@rowscont

总是

null

。在过程开始时设置

@rowscont=0

有帮助

“输出参数中没有任何内容”是什么意思？它是0？是的，它是0。但我的过程应该返回受影响的行数。否？如果使用

SET@rowscont=0启动程序，请尝试helps@PeterB你是个男人！！那件简单的事就像我脑袋里的斧头。非常感谢！您应该签出并停止使用
.AddWithValue（）
-这可能会导致意外的结果…我也使用过ExecuteOnQuery。它给了我0。编辑和包括如何获得价值@但我在SP或C#中没有使用TempRowCount。是吗？这给了我错误@TempRowCount未声明。当您接受某种回报时，使用输出参数是很好的。对吧？哇。美好的快速查看您的过程嵌套子查询，告诉我慢的原因。在多个级别嵌套子查询不是很好使用。
var result = cmd.ExecuteScalar();