SQL查詢效率

Question

我有一個工作查詢，不確定它是否有效。

表列：

1. P_TYPE：可以是字符串賣出，cancelsell，銀行，cancelbank要執行
2. ID
3. FID
4. 單元

操作：

1. SUM（單位）爲每個過程類型銷售，取消銷售，銀行，取消銀行。
2. SUM（單位賣出） - SUM（單位cancelsell），SUM（單位銀行） - SUM（單位cancelbank）

注意：我還檢查ID和每個FID選擇，雖然我需要檢查所有選擇相同的值。

現有的查詢：

select sell-cancelsell scount, bank-cancelbank bcount from 

    (select sum(a.unit) as sell from table1 a where 
    a.p_type = 'Sell' and a.id=1 and a.fid=2), 

    (select sum(c.unit) as cancelsell from table1 c where  
    c.p_type = 'CancelSell' and c.id=1 and c.fid=2), 

    (select sum(b.unit) as bank from table1 b where  
    b.p_type = 'Bank' and b.id=1 and b.fid=2), 

    (select sum(d.unit) as cancelbank from table1 d where 
    d.p_type = 'CancelBank' and d.id=1 and d.fid=2) 

是不夠好？如果任何人都可以建議一種更高效的方法，那就太好了。

Answer 1

你可以做到這一點

select 
sum(Case when a.p_type = 'sell' then a.unit else null end) as sellUnit, 
sum(Case when a.p_type = 'CancelSell' then a.unit else null end) as CancelSellUnit, 
sum(Case when a.p_type = 'Bank' then a.unit else null end) as BankUnit , 
sum(Case when a.p_type = 'CancelBank' then a.unit else null end) as CancelBankUnit 
from table1 a where and a.id=1 and a.fid=2 

Answer 2

試試這個：

SELECT 
     SUM(CASE WHEN P_TYPE = 'SELL' THEN UNIT END) - 
     SUM(CASE WHEN P_TYPE = 'CANCELSELL' THEN UNIT END) AS SCOUNT, 
     SUM(CASE WHEN P_TYPE = 'BANK' THEN UNIT END) - 
     SUM(CASE WHEN P_TYPE = 'CANCELBANK' THEN UNIT END) AS BCOUNT 
FROM TABLE1 
WHERE ID=1 AND FID=2 

Answer 3

select temp1.sumunit - temp2.sumunit,temp3.sumunit-temp4.sumunit from 
(select p_type,sum(unit) as sumunit from table1 
group by p_type) as temp1 
inner join 
(select p_type,sum(unit) as sumunit from table1 
group by p_type) as temp2 on temp2.p_type = 'cancelsell' 
inner join 
(select p_type,sum(unit) as sumunit from table1 
group by p_type) as temp3 on temp3.p_type = 'bank' 
inner join 
(select p_type,sum(unit) as sumunit from table1 
group by p_type) as temp4 on temp4.p_type='cancelbank' 
where temp1.p_type='sell' 
and temp1.id = 1 and temp1.fid = 2 
and temp2.id = 1 and temp2.fid = 2 
and temp3.id = 1 and temp3.fid = 2 
and temp4.id = 1 and temp4.fid = 2