It seems to me that the Closed World Assumption demands that your example must return the "plainly wrong" result that it does:

This is the so-called "Closed World Assumption": Everything stated by the database, either explicitly or implicitly, is true; everything else is false.

The database in your example does not state, either explicitly or implicitly, that Amount is 10, therefore this is false. It also does not state that Amount is not 10, therefore this is also false.

In reply to Re^4: DBI: passing undef as an argument by dsheroh
in thread DBI: passing undef as an argument by fws

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