Question

I can do the following in 2 queries but want to make it simpler. Can this be combined in one query? If so how more efficient is it than doing two queries vs one?

query1: SELECT page_id, coupon_id from table_1 WHERE key = :key
query2: SELECT folder from table_2 WHERE page_id = table_1.page_id

For my final result I need to have a coupon_id from table_1, and a folder from table_2.

In query2 I need to use the page_id result from query1 to get the folder

Is there a simpler way to do this?

Answer 1

Use JOIN (LEFT, RIGHT or INNER is up to your needs):

SELECT 
    t1.page_id, 
    t1.coupon_id,
    t2.folder
FROM
    table_1 AS t1
    LEFT JOIN table_2 AS t2 ON
        t2.page_id = t1.page_id
WHERE
    t1.key = :key