如何选择多个表？

Question

country | total users count | active users count | inactive users count | discipline subscribers count | top discipline | study level subscribers count | top study level

表国家

country_id | short_name

表用户（如果状态= 1，则状态= 1无效时，状态= 2）

id | country_id | status 

表user_subscribed_disciplines

id | user_id |discipline_id

table announcement_disciplin

id | name

表user_subscribed_study_levels

id | user_id | study_level_id

表cat_study_levels

id | name

答案必须是这样的

country | total users count | active users count | inactive users count | discipline subscribers count | top discipline | study level subscribers count | top study level
USA     |       506         |          500       |     6                |    50                        |          PHD   |          90                   |  Social History
CAN     |       406         |          406       |     0                |    50                        |          POS   |          0                   |  Social History

Answer 1

尝试以下方法：

some dummy text with email <a href ='mailto:pk@email.com'/> and one more email <a href ='mailto:pk2@gmail.com'/> and another one <a href ='mailto:thirdemail@domain.com'/> plus some more text.

Answer 2

您应该使用条件语句，如下所示。不要忘记将“`”放到“用户”表中。

SELECT countries.short_name, COUNT(user.id), SUM(case when `user`.status = 0 then 1 else 0 end) as variablename FROM `user` RIGHT JOIN countries ON `user`.country_id = countries.country_id GROUP BY short_name;