A query that returns an empty result is usually a wrong WHERE clause. But there is one class of empty result that confuses even experienced people, because every row it filters on looks correct: NOT IN with a NULL in the subquery. The failure Two tables. Customers, and the orders they placed: CREATE TABLE customers (id int, name text); CREATE... Weiterlesen: The NOT IN trap: why your SQL query returns zero rows
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The NOT IN trap: why your SQL query returns zero rows
A query that returns an empty result is usually a wrong WHERE clause. But there is one class of empty result that confuses even experienced people, because…