create   FUNCTION fn_GetPNumPPInfoState (@PNum varchar(30))  
RETURNS varchar(1000)  AS  
BEGIN 
    Declare   @s   varchar(8000)   
    Set   @s=''   

    Declare @Product varchar(1000)
    Declare @PartsName varchar(100)
    Declare @PPItem varchar(100)
    Declare @StatusDes varchar(100)

    declare @mytb table(id int identity(1,1),
                Product varchar(500),
                PartsName varchar(500),
                PPItem varchar(100),
                StatusDes varchar(250))

    insert into @mytb(Product,PartsName,PPItem,StatusDes)
    select distinct PnumPrintInfo.Product,case when PNumPrintInfo.PartsName='' then PNumPrintInfo.Product else PNumPrintInfo.PartsName end PartsName ,
        '印刷' as PPItem,IsNull(PlanArrage.StatusDes,'未排程') as StatusDes from (select * from PNumPrintInfo where PNumPrintInfo.PNum=@PNum) as PNumPrintInfo 
        left join (select * from PlanArrage where PlanArrage.PNum=@PNum) as PlanArrage on PlanArrage.PNum=PNumPrintInfo.PNum 
        and PlanArrage.ProductName=PNumPrintInfo.Product and PlanArrage.JSName='印刷' --where PNumPrintInfo.PNum=@PNum
    union all
    Select  distinct PNumPPInfo.Product,case when PNumPPInfo.PartsName='' then PNumPPInfo.Product else PNumPPInfo.PartsName end PartsName,
        PPItem,IsNull(PlanArrage.StatusDes,'未排程') as StatusDes from (select * from PNumPPInfo where PNumPPInfo.PNum=@PNum) as PNumPPInfo 
        left join (select * from PlanArrage where PlanArrage.PNum=@PNum) as PlanArrage on PlanArrage.PNum=PNumPPInfo.PNum --and PlanArrage.PNum=@PNum
        and PlanArrage.ProductName=PNumPPInfo.Product 
        and (PlanArrage.JSName=PNumPPInfo.TechReq or PlanArrage.JSName=PNumPPInfo.PPItem) --where PNumPPInfo.PNum=@PNum

    declare @i int
    set @i=-1
    while exists(select 1 from @mytb where id>@i)
    begin
        select top 1 @Product=Product,@PartsName=PartsName,
                @PPItem=PPItem,@StatusDes=StatusDes from @mytb where id>@i order by id desc

        if @s<>'' and @PPItem<>''
            set @s=@s+'、'
        if @PPItem<>''
            set @s=@s+@PartsName++'('+@PPItem+@StatusDes+')'
        --FETCH NEXT FROM ppCursor
        --into @Product,@PartsName,@PPItem,@StatusDes
    end

      Return   @s 
END

select Product,PartsName,PPItem,StatusDes,(直接计算成@s) from (select Product,PartsName,PPItem,StatusDes from table    union all
    Select  Product,PartsName,PPItem,StatusDes from table) a
--肯定快很多

------解决方案--------------------

尽量不要在select 里面嵌套select, 还有不要重复code  

page number 是不是数字类型， 如果不是，请换成数据类型，

尽量不要用tem table,  



SQL code

select distinct 
PnumPrintInfo.Product,
case when PNumPrintInfo.PartsName='' then PNumPrintInfo.Product else PNumPrintInfo.PartsName end PartsName ,
        '印刷' as PPItem,
IsNull(PlanArrage.StatusDes,'未排程') as StatusDes 

from  PNumPrintInfo  as PNumPrintInfo
        left join PlanArrage as PlanArrage on PlanArrage.PNum=PNumPrintInfo.PNum 
        and PlanArrage.ProductName=PNumPrintInfo.Product 
        and PlanArrage.JSName='印刷
        and PNumPrintInfo.PNum=@PNum