分页存储过程怎么准确获取总记录数

alter PROCEDURE [dbo].[Pro_Sys_Page2005]

 @TableName nvarchar(4000),        --表名

 @Columns nvarchar(4000) = '*',    --字段名(全部字段为*)

 @OrderColumns nvarchar(1000),        --排序字段(必须!支持多字段)

 @sqlWhere nvarchar(2000) = Null,--条件语句(不用加where)

 @pageSize int,                    --每页多少条记录

 @pageIndex int = 1            --指定当前为第几页

AS

BEGIN   

    Declare @sql nvarchar(4000),@totalRecord int, @TotalPage int, @StartRecord int,@EndRecord int; 

    if (isnull(@SqlWhere,'')<>'')

    begin

        set @TableName = @TableName + ' where ' + @sqlWhere--+ ' order by '+@OrderColumns

    end

    set @sql='select @totalRecord=count(1)from '+@TableName+''

    --print @sql

    EXECUTE sp_executesql @sql,N'@totalRecord int OUTPUT',@totalRecord OUTPUT--计算总记录数 

    --select @totalRecord=@@rowcount    

    --print @totalRecord

     select @TotalPage=CEILING((@totalRecord+0.0)/@PageSize) --计算总页数

     if @PageIndex<=0 

        Set @pageIndex = 1

    if @pageIndex>@TotalPage

        Set @pageIndex = @TotalPage

    set @StartRecord = (@pageIndex-1)*@PageSize + 1

    set @EndRecord = @StartRecord + @pageSize - 1

    set @sql = 'Select * FROM (select ROW_NUMBER() Over(order by ' + @OrderColumns + ') as rowId,' + @Columns + ' from ' + @TableName +') as t where rowId between ' + cast(@StartRecord as nvarchar) + ' and ' + cast( @EndRecord as nvarchar)

    print @sql 

    Exec(@Sql)

    select @totalRecord  as totalRecord ,@TotalPage as pageCount--总记录数,总页数

END

--如果 sql语句包含group by 那么记录总数就会取group by的最后一行的值

--应该怎么改才可以获取准确的记录总数呢

--@@rowcount 也试过不行

--代group by的sql 怎么获取总记录数呢