如何根据包含至少一个数组元素的相关表获取正确的行？

Question

I have posts and postWriters tables with one-to-many relationships. (I have also writers and follows tables).

Each post has been written by several writers collaboratively.

I want to get last 20 submitted posts which have been written by at least one writer I follow.

For example the writers that I follow:

$arrayOfWriterIds_IFollow = [3, 5, 123, 45, ..., 3456] // total 100 ids

I want to get last 20 posts, at least one of the writers I follow contributed to them.

Which mysql query gives me true results? Thanks.

Answer 1

Without knowing the full table structure, probably something like:

SELECT * FROM postWriters LEFT JOIN posts ON postWriters.post_id=posts.id WHERE postWriter.writer_id IN (your, followed, writers, here) GROUP BY posts.id ORDER BY posts.date DESC LIMIT 0,20;

Using IN to select your writers, GROUP BY to remove duplicate posts then ORDER BY DESC to get the latest by date and finally limit.