SQL's Sharp Edges

A compact SQL semantics book for readers who know set relations and need the sharp edges: bag duplicates, DISTINCT, NULL, WHERE truth, aggregates, grouping, and UNION ALL.

SQL Semantics

Relation vs Bag
SELECT Keeps Duplicates
DISTINCT Deduplicates
NULL is Not a Value
WHERE Keeps Only TRUE
Aggregates Skip NULL
GROUP BY
UNION vs UNION ALL