Question

下面给出了我的表

create table batches ( batchid int,free smallint,qty int)


INSERT INTO batches VALUES (2329, 0, 100);
INSERT INTO batches VALUES (2329, 1, 10);
INSERT INTO batches VALUES (2331, 0, 75);
INSERT INTO batches VALUES (2331, 1, 4);

此表将返回

 batchid free qty 
 2329    0    100
 2329    1    10
 2331    0    75
 2331    1    4

需要在栏 qty上执行划分，即在这种情况下100应该除以10（batchid应该相同））100/10（这里10是qty free = 1）

预期结果

Batchid  freelimit
2329     10
2331     18

Answer 1

WITH Queries (Common Table Expressions)

with a as (
    select 
      batchid,qty 
    from batches  
    where  free = 0 order by batchid 
)
, b as (
    select 
      batchid,qty 
    from batches  
    where  free = 1order by batchid 
)
select 
  batchid, floor((a.qty/b.qty))::real as freelimit 
from a inner join b using(batchid)

SQLFIDDLE-DEMO

Answer 2

你想在这里自我加入：

WITH d(batchid, free, qty) AS (
    VALUES (2329::int, 0::int2, 100::int), (2329, 1, 10),
           (2331, 0, 75),  (2331, 1, 4)
)
SELECT a.batchid, a.qty/b.qty
  FROM d a
  JOIN d b ON a.batchid=b.batchid AND b.free=1
 WHERE a.free=0;

在postgresql中选择查询中的分区

2 个答案: