Job Interview Questions: Should I mention my new job at an open house/job interview?

I'm attending an open house interview with a retail store tomorrow. I just started a new job last week and I wouldn't mind having another job. When I go to this open house, or any job interview, do I mention I have a job? If so, How to convince them that I can work both jobs or that I will leave my old job if they (new job) pay is without making it look bad (that I will leave a job for another job if they offer more)? Or does it really matter?

5 Helpful Rules to Successful Job Interviewing

Recommended Answer:
It might matter to them or it might not. I would say they might take someone who does not have any job at all before someone who does. So if you want another job, unless they ask you personally, I wouldn't tell them. You might be able to convince them you can do both, and hopefully the other job will offer more $ money!

Preparing For a Job Interview - How to Ace Your Job Interview and Jumpstart Your Career