Comparing timestamp to current time from database

Question

I need to test current time against a datetime from database, if it has been 30 mins then execute code, if not then dont. This is where I am at and I am stuck:

Answer 1

I like to use unix timestamps in this situation.

$timest = date('u'); // gets the unix timestamp
$q = "SELECT id 
      FROM `dwCache` 
      WHERE {$timest} - UNIX_TIMESTAMP(`timestamp_col`) > 1800";

Explanation:

This basically calculates the difference between the current time and the time in the table column. If it's higher than 1800 (30 minutes), it will select the row, and your PHP code will be executed.

Advantages

There are some advantages to using this instead of the PHP check you started doing. You will select fewer rows, thus occupy less memory.

PS:

Thumbs up for using MySQLi !