Creating Master Detail Combo Box

This sort of thing is easily accomplished in the designer. You'll need to drag two data adapters (one for the master data and one for the detail) and set them up with the wizard. Next drag a dataset to the design surface and set it up with 2 tables. Alternatively, you can right click on the master data adapter and create a managed dataset, then add an additional table for the detail. Finally add a relationship and you're done. Set the combobox datasources to the datatables. In the Forms_Load event, read your data from the data adapters.