Postgresql查询以获取一年内每月的计数

我假设您要查找的是count为0的行。如果是这种情况，则可以在表中使用generate_series和左连接并添加数据：

    SELECt to_char(i, 'YY'), to_char(i, 'MM'),        count(id)    FROM generate_series(now() - INTERVAL '1 year', now(), '1 month') as i    left join users on (to_char(i, 'YY') = to_char(created_date, 'YY')   and to_char(i, 'MM') = to_char(created_date, 'MM') and login_type = 1)    GROUP BY 1,2;