Appendix C — SQL Cheat Sheet

C.1 Query order

SELECT
    category,
    COUNT(*) AS records
FROM analysis.dataset
WHERE year >= 2024
GROUP BY category
HAVING COUNT(*) >= 5
ORDER BY records DESC;

C.2 Join

SELECT
    a.id,
    a.name,
    b.value
FROM table_a AS a
LEFT JOIN table_b AS b
    ON a.id = b.id;

C.3 Find duplicates

SELECT
    id,
    COUNT(*) AS occurrences
FROM analysis.dataset
GROUP BY id
HAVING COUNT(*) > 1;