SELECT / UNION / etc. : Obvious recommendations: Always specify DISTINCT ... preferably do so explicitly ... and never specify ALL.
{"Image DocumentName": "SELECT / UNION / etc. :Obvious recommendations: Always specify DISTINCT ... preferably do so explicitly ... and never specify ALL.", "Image ImageDescription": "Unfortunately ... /  quote ex book  / : At this point in the original draft, I added that if you find the discipline of always specifying DISTINCT annoying, don\u2019t complain to me\u2014complain to the SQL vendors instead. But my reviewers reacted with almost unanimous horror to my suggestion that you should always specify DISTINCT. One wrote: Those who really know SQL well will be shocked at the thought of coding SELECT DISTINCT by default. Well, I\u2019d like to suggest, politely, that (a) those who are shocked at the thought probably know the implementations well, not SQL, and (b) their shock is probably due to their recognition that those implementations do such a poor job of optimizing away unnecessary DISTINCTs.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}