我的sql自定义分页

declare
@mainsql nvarchar(500),          --主语句
@tempsql nvarchar(500),          --临时变量
@ordersql nvarchar(500),         --排序语句
@ordertype int,                  --排序类型（非0代表降序）
@primarykeyfield varchar(30),    --主键字段
@pageindex int,                  --当前页索引
@pagesize int,                   --页尺寸
@wherecondition nvarchar(500),   --查询条件
@tablename nvarchar(50)          --表名
--
set @mainsql=N''
set @tempsql=N''
set @ordersql=N''
set @ordertype=1
set @primarykeyfield=N'id'
set @pageindex=1 --1273723
set @pagesize=100
set @wherecondition=N'cdate between ''2008-7-30 00:00:00'' and ''2008-7-30 23:38:13'''
set @tablename=N'mytable'
--
declare @topn int
set @topn=(@pageindex-1)*@pagesize
--
if(@ordertype!=0)
begin
    set @tempsql=N'<(select min'
    set @ordersql=N' order by [' + @primarykeyfield + N'] desc'
end
else
begin
    set @tempsql=N'>(select max'
    set @ordersql=N' order by [' + @primarykeyfield + N'] asc'   
end
--
if(@pageindex=1)
begin
    set @mainsql=N'select top ' + cast(@pagesize as nvarchar(500)) + N' * from ' + @tablename
    if(@wherecondition !='')
    begin
        set @mainsql = @mainsql + N' where ' + @wherecondition
    end
    set @mainsql = @mainsql + @ordersql
end
else
begin
    set @mainsql = @mainsql + N'select top ' + cast(@pagesize as nvarchar(500)) + N' * from ' + @tablename
    set @mainsql = @mainsql + N' where [' + @primarykeyfield + N']' + @tempsql + N'([' + @primarykeyfield + N'])'
    set @mainsql = @mainsql + N' from (select top ' + cast(@topn as nvarchar(500)) + N' [' +@primarykeyfield + N'] from ' + @tablename
    if(@wherecondition !='')
    begin
        set @mainsql = @mainsql + N' where ' + @wherecondition
    end
    set @mainsql = @mainsql + @ordersql + N') as tblTmp)'
    if(@wherecondition !='')
    begin
        set @mainsql = @mainsql + N' and ' + @wherecondition
    end
    set @mainsql = @mainsql + @ordersql
end
--print @mainsql
declare @parameters nvarchar(500)
set @parameters=N'@mainsql nvarchar(500),
                  @tempsql nvarchar(500),
                  @ordersql nvarchar(500),
                  @ordertype int,
                  @primarykeyfield varchar(30),
                  @pageindex int,
                  @pagesize int, 
                  @wherecondition nvarchar(500),
                  @tablename nvarchar(50)'
exec sp_executesql @mainsql,@parameters,
                  @mainsql,       
                  @tempsql,       
                  @ordersql,     
                  @ordertype,    
                  @primarykeyfield,
                  @pageindex, 
                  @pagesize,
                  @wherecondition,
                  @tablename
--
--计算总记录数
declare
@totalsql nvarchar(500),         --计算总记录数
@wherecondition nvarchar(500),   --查询条件
@tablename nvarchar(50),          --表名
@recordcount int                 --总记录数 --output
--
set @wherecondition=N'cdate between ''2008-7-30 00:00:00'' and ''2008-7-30 23:38:13'''
set @tablename=N'mytable'
--
set @totalsql=N'select @recordcount = count(*) from ' + @tablename
if(@wherecondition !='')
begin
    set @totalsql = @totalsql + N' where ' + @wherecondition
end
--print @totalsql
declare @parameters nvarchar(500)
set @parameters=N'@totalsql nvarchar(500),
                  @wherecondition nvarchar(500),
                  @tablename nvarchar(50),
                  @recordcount int output'
exec sp_executesql @totalsql,@parameters,
                  @totalsql,
                  @wherecondition,
                  @tablename,
                  @recordcount output
select @recordcount as 'recordcount'