Re: Null values

In article <0D18940A29184D41AF9D369D0BD40D01829280@exch2k.emsg.darden.com>, JDrabb@darden.com (James Drabb) wrote: > What is the best way to check for a null value returned by a DB. > Would something like if ($row['fldUserName'] != False) be reliable > enough? Checking it in the database is your best bet. For instance, MySQL's syntax uses "is [not] null", i.e. "select foo from bar where bar is null". One gotcha to watch out for if you decide to check later in the process: make sure that the database result function you're using will return null values. For example, mysql_fetch_row(), does not. PHP's loose typing means that a null value will evaluate as false, but it's up to you to decide whether other values that evaluate to false (including zero values and empty strings) can be permissable values there too. My preference is to code what I mean, so that later there's no chance that an assumption that once seemed "implicit" suddenly is the source of a seemingly baffling inconsistency. If you want to check specifically for a null, use either "is_null()" or "===null". If any false-evaluating value will do, use "== false". If only boolean false is allowed, use "===false". For other occasions, there are also the alternatives of empty() and !isset(). It's worthwhile to learn the differences between each of these methods. The differences seem subtle or even trivial at first, but treating them as interchangeable is a dangerous habit to get into. -- CC