More Pitfalls of the MINUS comparison

When I did my presentation at APEX Connect, Erik van Roon explained another pitfall of my MINUS approach to compare the content of two views to me – something some people already tried to show me and failed (well, I failed getting the point).

Let’s start with the same situation as in the last example, a small list of Star Wars characters and the movie episodes in which they appear:

IDCharacterEpisodes
1Darth Vader3, 4, 5, 6
2Luke Skywalker4, 5, 6, 7, 8
3Rey7, 8

Now let’s assume we are forced to do overwork by the sithlord in charge, it’s 3 am, we are terribly tired and create a new view but miss the group by statement:

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Pitfalls of the MINUS-comparison

My work includes a lot of database views because they work as a kind of public API in our case. Since I started talking about self-testing and utPLSQL, the MINUS-comparison has always had its place when assuring that a new, reconstructed view has the exact same content as the old one.

However, I did it wrong until recently when I discovered a major pitfall.

For I like to tell stories let’s start with a Star Wars scenario again: We have a table which contains all the Star Wars characters and another table which holds information in which of the “Episode”-movies they appeared.

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