Returning NULL from a database-side Java function

[Alan Burlison]

I have a Java database-side function that does a simple lookup of a 
string on a reference table and returns the corresponding integer.  If 
the string can't be found I want to return NULL, but if I return a Java 
null I get a database exception rather than the desired behaviour:

Error: java.sql.SQLException: The exception 
'java.lang.NullPointerException' was thrown while evaluating an 
expression., SQL State: 38000, Error Code: -1

How do I return a 'database' NULL from a database-side Java function?

Thanks,

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Alan Burlison
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