How to test if variable is null

[Mack Lobell]

Hi!

I'm using a JDBC sampler to get data from a database. Sometimes the fields in 
the databse is null and my variables in the sampler will also be null. If I use 
the variable in a Response Assertion it always fails because the variable is 
null.

If a variable is null how can i test if the variable==null and variable!=null?

Is there a better control than a Response Assertion to use?

Any help is appreciated.

Thanks!