SQL 語句中union all和order by同時使用

          最近做的一個財物管理系統中查詢過期或逾期的存儲過程，返回 “財物所屬的案件名稱”，“財物名稱”，“財物編號”，“ 過期或逾期時間 ”（超期或逾期前7天開始預警）。

遇到“ union all 內不能使用  order by ”的問題，百度了很久，都沒有一個找到一個好的解決方案。最終還是自己實現了，記錄一下。

 

為什么用存儲過程，非得用union all 而不在程序中拼接表數據？

          這個 存儲過程不是供我們Web程序使用的，它是提供給運行在服務器上的C/S程序調用（ 用來投放到機房外的LED顯示屏 ）。

因為這個C/S程序不是我們寫的，別人要求用存儲過程並一次性返回超期和預期的數據。

當時我正在客戶那里安裝這個系統，這個功能是客戶臨時加的，所以就匆忙趕了一個，當時沒排序，回來后整理時才遇到這個問題。

涉及到的數據庫表（字段）：

 案件表【 AnJian 】 :（Id,案件名稱【anjianmingcheng】）

財物表【 CaiWu 】 :（Id,所屬案件【Id]anjianId】,財物編號【caiwubianhao】,財物名稱【 caiwumingcheng】,保存指定的保存結束時間【caoqi】 ）

財物調用記錄表【 CaiWuDiaoYongJiLu   】 :（Id,被調用財物Id【caiwuId】,調用時指定的歸還時間【yujingTime】）

注 保存結束時間和調用歸還時間不能為空，如果是長期會在程序中指定一個超大的時間值（9999/12/30）。

 

最初版本：

ALTER proc [dbo].[pr_get_time_limit]

as

select 
    cast(a.anjianmingcheng as varchar(100))  as anjianmingcheng,
    cast(c.caiwumingcheng as varchar(100))  as caiwumingcheng,
    cast(c.caiwubianhao as varchar(100)) as caiwubianhao,
    case 
        when datediff(day,c.caoqi,getdate())> 0 then '保存超期'+cast(abs(datediff(day,c.caoqi,getdate())) as varchar(50))+'天'
        else cast(abs(datediff(day,c.caoqi,getdate())) as varchar(50))+'天后保存超期'
    end as state,
    c.caoqi as tagtime 
from SACW_CaiWu c 
left join SACW_CaiWuDiaoYongJiLu as d on c.Id=d.caiwuId
left join SACW_AnJian as a on c.anjianId=a.id
where c.jiazhijine>0 and getdate()>dateadd(day,-7,c.caoqi) or  c.kucunshuliang>0 and getdate()>dateadd(day,-7,c.caoqi)

union all

select 
    cast(a.anjianmingcheng as varchar(100))  as anjianmingcheng,
    cast(c.caiwumingcheng as varchar(100))  as caiwumingcheng,
    cast(c.caiwubianhao as varchar(100))  as caiwubianhao,
    case 
        when datediff(day,d.yujingTime,getdate())> 0 then '歸還逾期'+cast(abs(datediff(day,d.yujingTime,getdate())) as varchar(50))+'天'
        else cast(abs(datediff(day,d.yujingTime,getdate())) as varchar(50))+'天后歸還逾期'
    end as state,
    d.yujingTime as tagtime 
from SACW_CaiWuDiaoYongJiLu d 
left join SACW_CaiWu c on c.Id=d.caiwuId
left join SACW_AnJian as a on c.anjianId=a.id
where d.jiazhijine>0 and getdate()> dateadd(day,-7,d.yujingTime) or  d.caiwushuliang>0 and getdate()>dateadd(day,-7,d.yujingTime)

 

優化后的代碼：

ALTER proc [dbo].[pr_get_time_limit]

as

DECLARE @TempTime  datetime
SET @TempTime = DATEADD(DAY,7,GETDATE())

SELECT 
a.anjianmingcheng as [anjianmingcheng],
t.cm as [caiwumingcheng],
t.cb as [caiwubianhao],
t.tagtime as [tagtime],
case 
    when t.orderby = 0 then 
        case
            when t.timeSpan > 0 then '調用逾期'+cast(t.timeSpan as varchar(50))+'天'
            --when t.timeSpan = 0 then '即將逾期'
            else cast(abs(t.timeSpan) as varchar(50))+'天后調用逾期'
        end
    else
        case
            when t.timeSpan > 0 then '保存超期'+cast(t.timeSpan as varchar(50))+'天'
            --when t.timeSpan = 0 then '即將超期'
            else cast(abs(t.timeSpan) as varchar(50))+'天后保存超期'
        end
end as [state]
 
FROM (
    select 
        c.anjianId as aid,
        cast(c.caiwumingcheng as varchar(100))  as cm,
        cast(c.caiwubianhao as varchar(100))  as cb,
        datediff(day,d.yujingTime,getdate()) as timeSpan,
        d.yujingTime as tagtime,
        0 as orderby
    from SACW_CaiWuDiaoYongJiLu d 
    left join SACW_CaiWu c on c.Id=d.caiwuId
    where (d.jiazhijine>0 or d.caiwushuliang>0) and @TempTime > d.yujingTime

    union all

    select 
        c.anjianId as aid,
        cast(c.caiwumingcheng as varchar(100))  as cm,
        cast(c.caiwubianhao as varchar(100)) as cb,
        datediff(day,c.caoqi,getdate()) as timeSpan,
        c.caoqi as tagtime,
        1 as orderby
    from SACW_CaiWu c 
    where (c.jiazhijine>0 or  c.kucunshuliang>0) and @TempTime > c.caoqi
) as t
left join SACW_AnJian as a on t.aid=a.id
order by t.orderby,t.timeSpan

 

問題，最初版本中的代碼中datediff函數計算值怎樣用一個臨時變量存起來供后面使用，而不是重新計算。不知道這樣寫在存儲過程中會不會有性能損失（理論上的）。

 

網上其它相關解決方案：

關於union all中使用多個order by 子句引起的問題 

http://blog.chinaunix.net/uid-20449297-id-1676810.html

 

UNION ALL 子句不能包含ORDER BY的解決之道

http://www.itpub.net/thread-1718235-1-1.html

 

union all和order by一起使用出問題

http://blog.csdn.net/tobeistdo/article/details/5613888

 

order by 和union all 如何共存

http://zhidao.baidu.com/link?url=GNpYMvin_xvKTQWrLMwHuoWg1yJtt0HODDLQYclj-tEuHJubI9UCJ4Uvm6qnP5eJL1sz8nKrKjM69OFHLGZcYq

 

來自為知筆記(Wiz)