Adam, bud, this is an advanced maneuver, but can be done. I'm a professional, so if you're going to try this, follow my advice exactly!
First, show no interest in her. Don't look at her, don't talk to her, don't think about her, don't do *ANYTHING* that would make her remember you. This is key!
Then the next day, go back to the bar around 6:00 PM, or before the place really starts to get crazy. If she remembers you from the other night, she'll think you're a stalker and it's over. Game, set match. You're done.
Look busy and disinterested. Grab a stool, order a beer and say, "Man, I was here last night and it was zoo! Is it always like that on Thursday nights?" or whatever night it was.
She'll reply with some small talk. Next, you have exactly one sentence to demonstrate that you're not hitting on her (even though you are), and that you're a gentleman (she deals with ***s nightly).
And that sentence is, "well you seemed to handle it well. Hey, I'm meeting up with a girl later tonight, what's a sorta romantic bar around here I could take her?"
Get into a conversation about bars, segue into relationships, the conversation will flow easily and you will have her. Tell her how easy it was to talk to her and ask her for her phone number or email address.
Jack