Assume you have written a large data set of good-weather, low zenith-distance Crab data with the following query to a file. The following will give you a few example of how you can make use of that in your analysis. To speed up things or decrease the file size (715MB), you might want to add additional cuts depending on your analysis. If you want to apply a Theta-square cut, please refer to DatabaseBasedAnalysis#Dataretrieval.

SELECT
   Events.MeanX,
   Events.MeanY,
   Events.Width,
   Events.Length,
   Events.CosDelta,
   Events.SinDelta,
   Events.M3Long,
   Events.SlopeLong,
   Events.Leakage1,
   Events.NumIslands,
   Events.NumUsedPixels,
   Events.Size,
   Position.X,
   Position.Y
FROM
   Events
LEFT JOIN Position USING (FileId, EvtNumber)
LEFT JOIN RunInfo  USING (FileId)
WHERE
   fSourceKey=5
AND
   fRunTypeKey=1
AND
   FileId BETWEEN 170800000 AND 180800000
AND
   fZenithDistanceMax<35
AND
   fR750Cor>0.9*fR750Ref