Change background color automatically

Here's the trick...

First I created AI files with single colored rectangles (they can be very small). Then saved them as blue.ai, green.ai, red.ai and so on...

In your Excel file, add a new column. At the beginning of this data field name, add a @ character. Indesign will now recognize this as an image field. (see Merge data to create form letters, envelopes, or mailing labels in Adobe InDesign for more information on this process).

Then add the paths to the right image in the following cells.

You should end up with something like this:

In Indesign, choose Content Placement Options from the Data Merge panel menu and select Fit Images To Frames.

Finally, all you have to do is to create two frames: one text frame for your text data fields and one graphic frame to place your background image. Adjust, place graphic frame behind and you're good...