Tag
duplicate-elimination
- Oct 4, 2023 Relations as Sets: Why the Relational Model Excludes Duplicate Rows How Codd defined a relation as a subset of a Cartesian product, what follows from value-based identity, and why SQL tables are multisets instead. databases
- Jul 27, 2022 Grouping, Duplicate Elimination, and Grouping Sets What a GROUP BY actually computes, how the sort-based and hash-based forms differ in output order, and how ROLLUP and CUBE collapse into one scan. databases