Run A Query In Trigger

What is the best way to submit a query in a trigger?
For example:
$idvalue=$record->display('somecolum');
Run following query and store date:
select col1,col2 from table where id='$idvalue';
Thanks.
For example:
$idvalue=$record->display('somecolum');
Run following query and store date:
select col1,col2 from table where id='$idvalue';
Thanks.