Antipattern: Solve a Complex Problem in One Step
Explore the risks of trying to solve complex database problems in one SQL query. Understand how this approach can cause Cartesian products, lead to inaccurate results, and increase difficulty in debugging and modifying code. Learn methods to manage query complexity by breaking down tasks into simpler queries for better performance and maintainability.
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SQL is a very expressive language — you can accomplish a lot in a single query or statement. But that doesn’t mean it’s mandatory or even a good idea to aim to solve every problem in one line of code. Do we have this habit with any other programming language we use? Probably not.
Unintended products
One common consequence of producing all our results in one query is something called a Cartesian product. This happens when two of the tables in the query have no condition restricting their relationship. Without such a restriction, the JOIN for the two tables pairs each row in the first table to every row in the other table. Each such pairing becomes a row of the result set, and we end up ...