SQL 计算性别的唯一出现次数

Question

我有 3 个表（人口统计）、（LINK）和（入学）

SELECT SUM(CASE dmg.dmg_Sex WHEN 'Male' THEN 1 END) AS male,
       SUM(CASE dmg.dmg_Sex WHEN 'Female' THEN 1 END) AS female,
FROM Demographic dmg
JOIN LINK lnk ON lnk.lnk_dmgID = dmg.dmg_ID
JOIN Admission adm ON adm.adm_ID = lnk.lnk_admID
WHERE adm.adm_ReferralDate >= '01/01/2011' AND adm.adm_ReferralDate <= '31/03/2011'

我正在尝试对日期范围内的性别求和。但这不起作用，我走在正确的轨道上吗？

仅在没有 SUM 和 CASE 的情况下执行普通查询 100%。

Answer 1

使用 GROUP BY

SELECT dmg.dmg_Sex, COUNT (dmg.dmg_Sex)
FROM Demographic dmg
JOIN LINK lnk ON lnk.lnk_dmgID = dmg.dmg_ID
JOIN Admission adm ON adm.adm_ID = lnk.lnk_admID
WHERE adm.adm_ReferralDate >= '01/01/2011' 
AND adm.adm_ReferralDate <= '31/03/2011'
GROUP BY dmg.dmg_Sex

Answer 2

SELECT SUM(CASE dmg.dmg_Sex WHEN 'Male' THEN 1 END) AS male,
       SUM(CASE dmg.dmg_Sex WHEN 'Female' THEN 1 END) AS female
FROM Demographic dmg
JOIN LINK lnk ON lnk.lnk_dmgID = dmg.dmg_ID
JOIN Admission adm ON adm.adm_ID = lnk.lnk_admID
WHERE adm.adm_ReferralDate >= '01/01/2011' AND adm.adm_ReferralDate <= '31/03/2011'

SQL 计算性别的唯一出现次数

SQL count unique occurrences of gender

sql

sql-server

sql-server-2008