On 18/09/15 12:38, Lester Caine wrote: > Forget enum and more than three values in a variable ... > > For SQL data coming from any decent database each variable can either > have a value in, ( which may be an empty string ) or be NULL. The NUMBER > of fields returned does not matter, a query returning a single record > can have a variable so the third condition is that rather than a field variable NUMBER OF FIELDS so
> being NULL, it does not exist, so testing for isset() only works for a > field that 'is set' and empty() only works with an empty value. Checking > for the field being present but NULL needs is_null() but THAT throws a > notice for those fields which have not been returned in this particular > result set. And one scenario here is that the database scheme actually > needs updating - but that should be handled differently - however a > system may have picked up an old copy of the data by mistake and the > missing fields need handling cleanly. > > We are not talking about the number of states stored IN a variable, but > just what a variables own states are. Adding another variable to > enumerate what say 'a date relates to' is a different matter. The date > value can be a valid date ( and genealogical date goes back before most > 'empty' date values ) or NULL indicating no date set OR the variable can > be missing from the result set. If you add in 'empty' one might say we > have for distinct states? FOUR distinct states ( and date is a good example here since 'empty' on something like MySQL is a valid date genealogically ) -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
