Guided Notes
Introduction to SQL
SELECT, filtering, and aggregation basics.
SQL (Structured Query Language) is how you ask a relational database for data. A SELECT statement names which columns you want and from which table.
WHERE filters individual rows before grouping; GROUP BY collects rows into buckets so you can aggregate (SUM, COUNT, AVG) per bucket; ORDER BY sorts the final result.
The same result can often be reached by more than one correct query — what matters below is the rows your query returns, not the exact SQL text.