SQL Query to add one columns value to another colum

[BirdOPrey5]

OK So I had several add-ons installed at once... First the Casino which stored cash as casino_cash in the user table... then I had the Gameroom which uses gameroom_cash. Also I have stock trader that doesn't store any value in the user table but can use any field I set. After upgrading to the Gameroom I never changed the field in Stock Trader to gameroom_cash until today so for sometime they were being tracked separately. What I need to do now is run a query where I set the gameroom_cash value to itself+casino_cash value- if it was a php variable it would be something like gameroom_cash = gameroom_cash + casino_cash- but I don't know how to do this as a sql statement. I searched google but most entries that came up were for me to add a new column rather then add value to a column.