Question

我有一张桌子，我希望在特定列的值最小且时间在9:15到10:00之间时获取行。

这是我的代码

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我希望得到类似的东西：

Select time, size, sym, price FROM test WHERE 
price = (Select MIN(price) from 
(select time, size, price from test where sym = 'PTX' And date = '2014-01-02' And time >=  '9:15'  And time <'10:00'  ) as test1
)
Group By sym, time, size, price;

相反，我正在

     time     |  size  | sym  | price 
--------------+--------+------+-------
 9:53:32.486 |    100 | PTX  |  2.42

Answer 1

您需要将主查询中的WHERE与子查询匹配。目前，您正在查找条件的最低价格，但未对主查询应用相同的条件。试试这个：

Select time, size, sym, price FROM test WHERE 
price = (Select MIN(price) from 
(select time, size, price from test where sym = 'PTX' And date = '2014-01-02' And time >=  '9:15'  And time <'10:00'  ) as test1
) and sym = 'PTX' And date = '2014-01-02' And time >=  '9:15'  And time <'10:00'
Group By sym, time, size, price;

Answer 2

一种方法只使用order by并将结果限制为一行：

Select time, size, sym, price
from test 
where sym = 'PTX' And date = '2014-01-02' And time >= '9:15' And time < '10:00'
order by price
limit 1;

注意：某些数据库将limit拼写为fetch first 1 row only，在top 1中使用select，或者使用类似的方法来限制返回的行数。

sql找到满足某些条件的最小值

2 个答案: