Restrict competition entry to once per day

Question

I'm writing a PHP competition script for a members site that needs to restrict entries to one per day per member. So far I have the following MySQL code:

SELECT ce_id 
  FROM competition_entries 
 WHERE ce_c_id = '$c_id' 
       AND ce_sub_id = '$user_id' 
       AND cte_date >= SYSDATE() - INTERVAL 1 DAY

• ce_c_id is the competition ID,
• ce_sub_id is the member ID, and
• cte_date is a MYSQL datetime stamp for the entry.

It's hard for me to test from where I am now & I need to find a solution, so I'm hoping someone can tell me whether this is restricting to once-per-day or once-per-24hrs - and point me in the right direction if it's the latter.

TIA :)

Answer 1

Create a primary key composed of the user_id, competition_id and a date type column.

To check if the user has already placed an entry:

select count(*)
from competition_entries
where ce_c_id = '$c_id' 
    AND ce_sub_id = '$user_id' 
    AND cte_date = current_date()