I lock rows based on 2 columns, "status" and "locktime". The idea is: if
the locktime has older than some age ( e.g. 1 minute), then the "status" bit
can be ignore, i.e. the lock expires. The problem I have is: if the
"locktime"
is "NULL" (this set when the lock is removed), then I can't get the age.
Is there a way to find the age of a column whose value can be or is "NULL"?
