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SQL Tips and Tricks
SQL tips and tricks. Contribute to ben-n93/SQL-tips-and-tricks development by creating an account on GitHub.
As NULL represents Unknown the SQL engine can't verify that the value being checked is not present in the list. When you have complex queries with multiple joins it pays to be able to trace back an issue with a value to its source. If I had to give one piece of advice to someone learning SQL it'd be to understand the order of execution (of clauses).
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