如何从具有一个唯一字段和另一字段的特定值的表中提取所有行？

Question

Here's what I'm looking to accomplish:

I have a table called "users_skills". The table consists of two fields, "user_id" and "skill_id". I want to pull all rows from the table that show a user has specific skills.

For example, I want to pull all users from "users_skills" who have skill_id 110, 120, and 130. If a user in "users_skills" doesn't have all 3, I don't want them in my results.

I've tried a simple AND (like users_skills.skill_id=110 AND users_skills.skill_id=120 AND users_skills.skill_id=130) but that didn't work.

How would I accomplish this? Thanks!

Answer 1

Try using a self-join:

SELECT us1.* FROM users_skills us1
  JOIN users_skills us2 ON us1.user_id = us2.user_id
  JOIN users_skills us3 ON us1.user_id = us3.user_id
    WHERE us1.skill_id = 110 AND us2.skill_id = 120 AND us3.skill_id = 130

I assume you actually want the data from the tables users and skills , in that case, you could use

SELECT users.*, skills.* FROM users
  JOIN users_skills us1 ON users.id = user_id
  JOIN users_skills us2 ON users.id = us2.user_id
  JOIN users_skills us3 ON users.id = us3.user_id
  JOIN skills ON skills.id = us1.skill_id OR skills.id = us2.skill_id OR skills.id = us3.skill_id
    WHERE us1.skill_id = 110 AND us2.skill_id = 120 AND us3.skill_id = 130