I'm trying to figure out a simple and efficient way to build part of an appointment scheduler. Basically, I have a SQL table with start and end times by date (the start and end times when a hairdresser is on the clock), and another table with existing scheduled appointments (includes time and date). What I need to do is create a list of available times in half hour increments to display in a datagrid, but I'm not sure where to start. Any ideas? This is a modification of an existing application, so I have limited ability to make changes to the existing tables, but I can add new tables and stored procedures.