select 项目，其中 id 包含在另一个表字段中

Question

I have the following database schema in sqlite3:

Basically, a member has multiple characters. A character plays in an activity (with a mode type) and has results for that activity (character_activity_stats)

I select all of the stats (activity / character_activity_stats) for a specific character and mode like so:

SELECT
*,
activity.mode as activity_mode,
character_activity_stats.id as character_activity_stats_index
FROM
    character_activity_stats

INNER JOIN
    activity ON character_activity_stats.activity = activity.id,
    modes ON modes.activity = activity.id

WHERE
    modes.mode = 5 AND
    character_activity_stats.character = 1

This works great.

However, now I want to select the same set of data, but by member (basically combine results for all characters for a member).

However, I am not really sure how to even approach this.

Basically, I need to retrieve all character_activity_stats where character_activity_stats.character is a character of the specified member (by id). Any suggestions or pointers? (I am very new to sql).

Answer 1

Join those 3 tables on the right keys:

select *
from character_activity_stats
join character on character_activity_stats.character = character.id
join member on member.id = character.member
where member.id = ?

If you don't need any data from member other than limit by id, then you leave that join off and just do character.member =? instead.

It's much easier if you use the same name for the primary and foreign keys (ie don't use id for the primary key). It also allows you use natural joins so you don't even need to give the join conditions. For the primary key to convention is usually _id. You id and _in in most of the tables, so I don't what is that is about.