SQL查询效率

Question

我有一个工作查询,不知道它是否有效.

表列:

1. p_type:可以是STRING卖出,取消卖出,银行,取消银行
2. ID
3. 瞎话
4. 单元

要执行的操作:

1. 每个流程类型的SUM(单位)出售,取消,银行,取消银行.
2. SUM(单位出售) - SUM(取消单位),SUM(银行单位) - SUM(取消银行单位)

注意:我也在检查每个选择中的id和fid虽然我需要检查所有选择的相同值.

现有查询:

    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)

够好吗？如果有人可以建议一种方法,使其更有效,那将是伟大的.

Answer 1

你可以这样做

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