SQL Extensions

Constraints

Narrow constraint validation recomputes not_null, unique, and foreign_key facts.

highlighted = computed this step

Constraints

The constraint surface validates a pinned child table against not_null, unique, and foreign_key checks. It reports violations without mutating the child rows.

finite table constraint validation\text{finite table constraint validation}

Constraint facts

The checker evaluates 3 constraints over 4 rows and finds 3 violations.

constraints=3,violations=3\text{constraints}=3,\quad \text{violations}=3

SQL extensions are rendered as tiny finite-table semantics; SQL dialect completeness, optimizer behavior, execution cost, full DDL behavior, and database-product claims are out of scope.

compiled summaryfactvaluerowCount4arity3rootKindcheck_constraints Constraintsuidemaildept1a102bNULL3a99NULLn10 constraint resultsnamekindpassedviolationCountnn_uidnot_nullno1uq_emailuniqueno1fk_deptforeign_keyno1

Summary

NULL keys are handled by the narrow rule in the compiler. Note: CHECK expressions, cascades, deferred checks, and general DDL are out of scope.

validation only\text{validation only}