The Birthday song

As today (march4) is b-day, I thought this would be appropriate. Honestly though, this song is really wierd as far as chord analyzing goes. The pickup actually starts on a 4 chord, and then moves to the I chord. This has always confused me. It moves between IV, V, and I. It has a two measure exposition that states the main melody and then repeats it with only a one note variation. The next two measures then consist of a larger variation or development of the melody with an emphasis on the seventh. The last two measures are then a recapitulation of the melody only slightly varied. The melody itself is only 1 measure long, ending on a HC each time. And then the end ends on a nice, happy PAC. This song is made up of 3 distinct little periods that are symmetrical and closed because it starts and ends in the same key. Its interesting how much you can get out of one little song, and I'm sure its not everything....but it is a stab. Ok, well I can't afford to pay anymore copyright royalties by playing this song anymore.....soooo goodnight!