MySQL 5.5 Release Notes
If a stored procedure exits with an unhandled exception,
modified values of OUT
and
INOUT
parameters are not propogated back to
the caller.
If an exception is handled by a CONTINUE
or
EXIT
handler that contains a
RESIGNAL
statement, execution of
RESIGNAL
signals the exception
(that is, the information that existed before entry into the
handler). If the exception is an error, the values of
OUT
and INOUT
parameters
are not propogated back to the caller.