Inaccuracy in a case of Quantified Comparison Subqueries of the type all of the Structured Query Language

Authors

Sánchez, Javier

Abstract

The verification of the subquery quantified type all has the objective of demonstrating how in some cases they do not give the expected result that by logic it should be. It begins by describing the problem, which is a case of using the quantified subquery of type ALL, then in the Framework of Basic Technologies the concepts of the null value, the Where clause of the Select statement, the types of subqueries, especially the most complex one, which is the quantified one. Finally, the problem is validated using three tools that use the structured query language, in which two give the same logically wrong result in the use of a case with the quantified sub query All, it is also shown that an old tool is robust in this case fulfilling the logic of the results.