[英]How can I separate two columns of count by group by?
当我这样做时,
SELECT id, gender, count(1)
FROM class_student
WHERE id = 1
GROUP BY gender
我明白了
id gender count
--------------------
1 female 10
1 male 5
我怎么能得到这个?
id female male
---------------
1 10 5
以下查询是否是正确的方法?
SELECT
id,
(select count(1) from class_student
where id = 1 AND gender='female') AS female,
(select count(1) from class_student
where id = 1 AND gender='male') AS male
FROM class_student
GROUP BY id
你可以使用带有大小写的选择
SELECT id
, sum(case when gender = 'male' then 1 else 0 end) male,
, sum(case when gender = 'female' then 1 else 0 end) female
FROM class_student
WHERE id = 1
GROUP BY id
您可以使用CASES :
SELECT id, SUM(case when gender = 'male' then 1 else 0 end) male, SUM(case when gender = 'female' then 1 else 0 end) female
FROM CLASS_STUDENT
WHERE id = 1
GROUP BY id;
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