继续我的问题
summarizing-two-conditions-on-the-same-sql-table,我添加了一个RATIO列,它只是一个SUM(…)列除以第二个SUM(…)列：
SELECT
COMPANY_ID,SUM(CASE WHEN STATUS IN (0,1) THEN 1 ELSE 0 END) AS NON_BILLABLE,SUM(CASE WHEN STATUS IN (2,3) THEN 1 ELSE 0 END) AS BILLABLE
SUM(NON_BILLABLE)/SUM(BILLABLE) AS RATIO
FROM TRANSACTIONS
GROUP BY COMPANY_ID
像这样定义RATIO看起来很漂亮和干净,但显然也是forbidden by SQL.
为了使查询正常工作,我只复制了NON_BILLABLE和BILLABLE的CASE语句.
SELECT
COMPANY_ID,3) THEN 1 ELSE 0 END) AS BILLABLE
SUM(CASE WHEN STATUS IN (0,1) THEN 1 ELSE 0 END)/SUM(CASE WHEN STATUS IN (2,3) THEN 1 ELSE 0 END) AS RATIO
FROM TRANSACTIONS
GROUP BY COMPANY_ID
是否有更好,更清晰(非冗余)的方式来编写此查询？
解决方法
使用：
SELECT x.company_id,x.non_billable,x.billable,x.non_billable/x.billable AS RATIO
FROM (SELECT t.company_id
SUM(CASE WHEN STATUS IN (0,3) THEN 1 ELSE 0 END) AS BILLABLE
FROM TRANSACTIONS
GROUP BY t.company_id) x
