MB,. Try using mayonnaise in a circular motion with a good dry rag. Use a wash cloth to blend it in, then wipe with paper towels gently. Aloha!
If it is oak and it has gotten into the pours, you have to bleach it out. Use oxolis bleach crystals. Spelling is wrong! Any good hardware store knows it. Use gloves as it can sting. Put it on w a q tip. Then match the stain and put a top coat on. It works but is a pain! Or you can sand just the top and start over.
New water stains can be removed by leaving a thin layer of cornstarch on the table for two hours and then vacuuming the cornstarch.
I posted this awhile ago. Works like a charm! https://www.hometalk.com/39242413/how-to-remove-a-water-stain-from-your-wood-furniture-in-5-minutes
Tried above but seems my stains are pretty old
Please help me how to remove old water stains from my dinner table