SQL: Joins, Duplicates, Set Operations
DDL, DML, DCL and TCL statements; DELETE versus TRUNCATE versus DROP; a table definition with every constraint kind; the logical evaluation order of a SELECT; inner, outer, cross and natural joins counted on one instance, including the left join whose WHERE filter silently turns it into an inner join; duplicates and DISTINCT; UNION, INTERSECT and EXCEPT with their ALL forms and the bag counting rules; LIKE, BETWEEN and NULL sort order. Every result was run on SQLite, and INTERSECT ALL and EXCEPT ALL on PostgreSQL.
