SQL Tutorial - NOT EXISTS | Database Tutorial 5i

Publié le: 09 avril 2020
sur la chaîne: Theoretical Computer Science

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In this lecture of the databases course we learn how to write (non-monotonic) SQL queries using EXISTS and NOT EXISTS. The (NOT) EXIST operation can be used to check whether a subquery computes a (non-)empty result. We will see that the subquery always should to be correlated with the outer query, and we will learn about variable scoping in SQL. We will discuss several examples and common mistakes.

This is the databases online course given at the Vrije Universiteit Amsterdam by Jörg Endrullis. The course objective is to obtain a good understanding of relational database systems from the user perspective. This includes the ability to develop conceptual database models, as well as key concepts and skills in relational database theory and practice.

Among others, we treat in this course the following subjects:
(a) entity–relationship diagrams for the design of database schemata,
(b) the relational database model and integrity constraints,
(c) SQL (structured query language) for retrieving information from relational databases,
(d) database normalisation and functiona dependencies (reasoning about good database design),
(e) transactions and concurrency control.

The slides are based on work by Peter Boncz and Torsten Grust.

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