Question

Let’s say I have this MySQL table:

OK.. see the type field? Type 0 is when a person KNOWS and a language and Type 1 is when a person is LEARNING that language.

and let’s say I have some data:

As you can see, member 3 corresponds with uid (user id). User 3 KNOWS Chinese because of the type 0 but where was User 1 is LEARNING Chinese because of the type 1.

And finally, let’s say I make a form. It has two select fields filled with an array of language selections. After a certain submit… $lang_learning outputs zh and $language_know outputs en. How would I find a person who speaks zh and is learning en without conflicting with the language field since you’re essentially looking for it twice?

Thanks.

Answer 1

You need a self join. Try this.

SELECT t1.uid 
FROM languages t1
INNER JOIN languages t2 ON t1.uid = t2.uid
WHERE t1.language = 'zh' AND t1.type = 0
  AND t2.language = 'en' AND t2.type = 1;