question

How can I create a data entry form in SharePoint Designer 2010 using one table to look up a value to insert into a different table? I have two SQL data sources, one to insert data and one to use as a drop down box. I can't find an answer on how to bind to the look up table on the form. EX: I need to enter a date, name, address and then have a field to look up a reason code from a different table. I then need to insert the form data into a master table. Any help is greatly appreciated.