Question

I have a table name wishlist. In this I have two fields user_id and product_id.
In a page, I will check if the $user_id and $product_id variables are found in this table.
If are they found in the same row then a found message is appeared, otherwise a not found message. It may only be found once.

How can I do this?

This is my wishlist table

user_id product_id
1       13
2       23

and suppose the $user_id = 1 and product_id = 13

Answer 1

Something like this should do the trick:

select exists (
    select 1
    from wishlist
    where user_id    = $user_id
      and product_id = $product_id
)

Some databases even have special optimizations for the select exists (select 1 ...) construct so they can short circuit it rather than finding all the possible matches.