Which columns may appear next to GROUP BY?
QuizMedium
Why do PostgreSQL and MySQL (with its default settings) reject this query?
SELECT dept_id, name, COUNT(*) FROM employees GROUP BY dept_id;
- name is neither in GROUP BY nor inside an aggregate, so a group of several employees has no single name to show
- COUNT(*) cannot be used with GROUP BY
- GROUP BY needs every column of the table
- dept_id must not be selected when it is grouped
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