Question

I’m trying to test a sql database that I created. To do so, I’ve got 2 tables: items and brands. Items store different fields including the name of a brand, and brands store other fields including a name. I would like to check that for each brand in items, there is a corresponding name in brands table. How would I do that ? I thought of something along the lines of:

"for each row in items"
if (count(select * from items join brands on items.brand = brands.name) == 0, select items.name, '');

But then I don’t know how to include the for statement in it… Any ideas?

Answer 1

You could try this:

SELECT items.name 
FROM items LEFT JOIN brands
    ON items.brand = brands.name
WHERE brands.name IS NULL
ORDER BY items.name

With this query you get all records from items table, join them with corresponing brands records (if they exists) and finally take the ones not having brands corresponding record.