This is what I have learned in getting only on row of data. You should write a derived field for each row of your data. Let's say you have a row of data for Date A, a row of data for Date B and a row of data for Date C.
Write a derived field for Date A, a derived field for Date B, and a derived field for Date C. Then you write a 4th derived field that adds Date A, Date B and Date C. The results will be your row of data.
Make sense? Let me know.