From the course: Advanced SQL: Logical Query Processing, Part 1

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Missing information and ternary logic

Missing information and ternary logic - SQL Tutorial

From the course: Advanced SQL: Logical Query Processing, Part 1

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Missing information and ternary logic

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- [Instructor] In 1970, Dr. Edgar F. Codd published his seminal paper, "A Relational Model of Data for Large Shared Data Banks", in which he introduced his relational model. It soon became apparent that in our less-than-ideal reality, missing data is a pain we must deal with. And only five years later, Codd introduced NULL as an indicator for missing data. In 1979, he further defined the semantics of NULL in his paper paper, "Transactions on Databases". NULL is one of the most controversial aspects of the relational model and of SQL. It introduced numerous anomalies and complexities and has been criticized by scholars and data practitioners throughout history. Trivia fact, Chris Date, one of the most highly regarded relational data model experts, a close collaborator of Dr. Codd and an author of key influential books on the relational model says, "NULLs undermine "the entire foundations of the relational model." Although Dr…

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