CS 221: Database Systems › Lesson 3 of 10

SQL Basics: SELECT, FROM, WHERE

Lesson 3 · OKSTEM College · AS Computer Science

SQL Basics: SELECT, FROM, WHERE

Study SQL Basics: SELECT, FROM, WHERE — complete the practice problems in your notebook.

Interactive Lab

Knowledge Check

Which SQL clause filters rows AFTER grouping?

WHERE filters before grouping.
Correct — HAVING filters aggregated groups.
ORDER BY sorts results; it doesn't filter.
LIMIT restricts output count, not group filtering.
📖 Quick Recap

WHERE filters individual rows before GROUP BY runs. HAVING filters groups after aggregation.

📖 Quick Recap

ORDER BY: ASC/DESC sorting. HAVING: filter on aggregate conditions.

📖 Quick Recap

LIMIT (or TOP in SQL Server) truncates results. HAVING filters groups based on aggregate conditions.

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