Mysql查询返回每个不同字段的出现次数

Question

我有下表，如何返回id

的每个status=pass的出现次数

id  status
111 pass
111 fail
333 pass
222 pass
333 pass
222 fail

以便结果集看起来像这样

id  num_occurrences
111 1
222 1
333 2

Answer 1

试试这个::

 select id, count(id) as num_occurrences from table where status="pass" group by id

Answer 2

查询可能看起来像那样

SELECT COUNT(id) AS num_occurrences FROM tableName WHERE status = 'pass'

但有一件事。 id通常是唯一的，你不应该称之为列名id