SQL：如何在SQL中过滤（WHERE）连接（ON）表？

Question

I have two tables (users and posts) and I want to write out all posts (among other things) by one user. I'm thinking I should use a JOIN and WHERE but I get an error for using WHERE.

This is my code:

SELECT username, post, joinDate, title, info FROM users 
    WHERE userId='18' 
    JOIN posts ON users.userId=posts.userId 
    ORDER BY date DESC

I'm new to this and perhaps there is a better way but I can't figure it out atm. Thankful for all answers!

Answer 1

The JOIN clause comes before the WHERE clause, after the FROM clause. First you join together all the tables you need, then you do your filtering with WHERE. Like this:

SELECT username, post, joinDate, title, info
FROM users 
JOIN posts ON users.userId=posts.userId 
WHERE users.userId='18'
ORDER BY date DESC