[firebird-support] Test VARCAHR for numeric

[sboyd...@gmail.com [firebird-support]]

Is there any way, within a stored procedure, to test a VARCHAR to see if it 
contains a valid number? I have a parameter that can contain different types of 
value and it would be nice to be able to know if CAST(param as BIGINT) is going 
to fail before an exception is thrown.