Re: datediff

[ifa thenb]

Hi Peter

This worked perfectly. Thanks

One part of the query I don't understand:

How does the DATEFIFF function serve both the IFNULL statement as well as the outside or broader statement.


The IFNULL statement tells mysql to calculated the difference between two dates whenever the dischared date is null, but how does it know to do the same for when the discharge_date is not null? If I remove the IFNULL statement I get:

1+ DateDiff (,admissin_date)
1 + DateDiff( ), admission date )

so somehow, the 1 + DateDiff( IfNull( discharge_date, CurDate() ) portion of the statement is serving both the IFNULL and broader statement

Paul