Hi CompGeekess,
So you're trying to filter a SQL data query to show the values based on a field. The first link describes a technique to set up all fields to filter based on another field. Unfortunately, this requires all of the data to be downloaded to the form on load. If there are only 100 sets of data, that should work fine, but if more than that, you'll want to do server side filtering with a web service (for example, Qdabra's DBXL).
Assuming you have <100 sets of data (and a fast net connection), you can pull the values into your form and use the technique Mike1428 describes to filter the items. You need to use a value (or attribute) that is the ID of the employee. For example, if you're selecting FullName, you can set the value of Telephone based on that. It's the Telephone where the FullName equals the FullName selected in the first dropdown. The xpath filter for that will look like Telephone[2DS\FullName=my:FullName] where 2DS is the secondary data source path where your data exists and my:FullName is the path to the field or attribute in your form's main data source.
If you aren't using a secondary data source to call the database and are instead using a main data source, then the technique Mike1428 describes does not apply to you. You need to query for the record whenever it changes. Add a rule to your FullName dropdown that queries the data connection for it.
Sorry this wasn't more detailed, but I would need to see your form. You can attach an XSN to this post and I will review.