Question

I have two tables I need to join together and I’m unsure how to do it. I’m still trying to learn how join works and I know there are a bunch of different kinds. Here are my tables:

laser    feature1   feature2   feature3
laser1   1          1          0
laser2   1          0          1
laser3   1          1          0


feature_name   feature_text
Feature #1     Text 1
Feature #2     Text 2
Feature #3     Text 3

How do I join these two tables together so I get only the feature_names and feature_texts where there is a 1 in the top table?

Answer 1

Here’s a better structure:

laser (Table)
-------------
laser_name, laser_id

feature (Table)
---------------
feature_name, feature_texts, feature_id

feature_laser (Table)
---------------------
laser_id, feature_id

Edit

If you want to see what lasers are associated with feature_id = 1, then you can join like this:

select laser_name from laser
    inner join feature_laser on feature_laser.laser_id = laser.laser_id
where feature_id = 1;

If you want to see what features are associated with laser_id = 1, then you can join like this:

select feature_name from features
    inner join feature_laser on feature_laser.feature_id = features.feature_id
where laser_id = 1;