Question

拥有此表（顶行是列名）：

security    quote_type      price
sec_1       bid             3.4
sec_1       ask             3.6
sec_2       bid             5.2
sec_2       ask             5.4
sec_3       bid             2.3
sec_4       ask             7.8

需要查询才能获得这些结果：

security    bid     ask
sec_1       3.4     3.6
sec_2       5.2     5.4
sec_3       2.3     null
sec_4       null    7.8

使用SQL Server。

感谢您的帮助！

Answer 1

您也可以使用条件聚合或pivot：

select security,
       max(case when quote_type = 'bid' then price end) as bid,
       max(case when quote_type = 'ask' then price end) as ask
from t
group by security;

Answer 2

您可以在桌面上的两个查询之间加入：

SELECT          a.security, bid, ask
FROM            (SELECT security, price AS bid
                 FROM   mytable
                 WHERE  quote_type = 'bid') a
FULL OUTER JOIN (SELECT security, price AS ask
                 FROM   mytable
                 WHERE  quote_type = 'ask') b ON a.security = b.security

SQL连接在同一个表的列上

2 个答案: