I have a list in SharePoint that is:
ID | Title | Job
1 | Bob | Painter
2 | John | Carpenter
....
I have a dropdown list in the form that lists all of the options (Bob, John, etc.). I have a hidden field, hdnJob, that apparently (I inherited this InfoPath form so I assume that is what it is for, looks like it from the code behind that I had to decompile from the DLL) stores whatever the Job value is for the selected item in the dropdown.
How can I make it so where when ddlPerson's selected value changes, hdnJob is updated to the Job value (ie if I select John, with ID 2, hdnJob changes to Carpenter)
edit: Mohamed got me headed in the right direction (thanks). The thing I was having issues with in regards to the instructures was selecting the underlying data connection's data. All I saw were the form fields. Make sure you click the dropdown at the top (for me, it was set as "Main" and then select the data connection's name. From there, I believe it was dataFields, and the field Job). Everything else he lists should have you good to go.