If null values are expected, you can include the returns null on null input clause when you create the function. For example:
create function job_of(jc integer) returns varchar(20) returns null on null input language java parameter style java external name 'SQLJExamples.job(int)'
You can then call job_of in this way:
select name, job_of(jobcode) from sales_emps where job_of(jobcode) <> “Admin”
When the SQL system evaluates the call job_of(jobcode) for a row of sales_emps in which the jobcode column is null, the value of the call is set to null without actually calling the Java method SQLJExamples.job. For rows with non-null values of the jobcode column, the call is performed normally.
Thus, when a SQLJ function created using the returns null on null input clause encounters a null argument, the result of the function call is set to null and the function is not invoked.
If you include the returns null on null input clause
when creating a SQLJ function, the returns null on null
input clause applies to all function parameters,
including nullable parameters.
If you include the called on null input clause (the default), null arguments for non-nullable parameters generates an exception.
