machenjie sql-professional-usage
Registry Trigger
Use when
- SQL or generated-query changes can alter NULL and three-valued logic, row cardinality, constraints, transaction or lock behavior, precision, ordering, or dialect semantics.
- Query or DDL behavior needs compatibility across data shapes, application versions, database versions, or migration phases.
Do not use when
- The open decision is datastore selection, domain modeling, ORM structure, deep plan tuning, transaction protocol, or migration orchestration without a SQL-specific semantic question.
- No SQL text, generated SQL, schema, constraint, database type, transaction, or engine behavior changes.
Skill Role
Protect SQL predicate and cardinality semantics, database invariants, parameter boundaries, numeric and temporal representation, dialect behavior, and SQL-visible compatibility.
High-Value Rules
- Model predicates as
TRUE,FALSE, orUNKNOWNacross filters, joins, constraints, aggregates, and ordering. - State row cardinality and multiplicity before joins, aggregation, windows, pagination, or upserts.
- Define deterministic tie-breakers for stable paging and first/last choices.
- Encode race-sensitive invariants in database constraints when the engine can own them.
- Declare transaction boundaries, isolation assumptions, lock order, retry class, read source, and visibility.
- Define units, precision, scale, rounding, instant/local meaning, timezone conversion, and driver representation.
- Parameter-bind external data values; map dynamic identifiers through a closed choice.
- Return a SQL semantic decision grounded in selected-engine/version verification, inspected evidence, and residual risk even when no Reference loads.
Anti-Patterns
- A result from tiny development data is treated as proof of cardinality, plan stability, lock behavior, or production cost.
NOT IN, an outer-join filter, an aggregate, or a uniqueness rule silently changes meaning when NULL or duplicate rows appear.DISTINCT,COALESCE, implicit casts, or floating-point storage hides an unresolved join, missing-value, type, precision, or consumer-contract defect.- A fixed row threshold or engine-specific online-DDL recipe is applied without the current engine, version, data shape, lock behavior, and release path.
Stop Conditions
- Route transactions, migrations, plans, indexes, and repositories to their specialist owners.
- Route public contracts, security, money, and timezone behavior to their specialist owners.
Output Contract
- SQL semantic decision with NULL cardinality constraints transactions locks precision parameter dialect migration risks and specialist routes
Targeted References
| Path | Type | Load when | Do not load when | Required by | Required output |
|---|---|---|---|---|---|
| benchmarks and patterns | benchmark-pattern | SQL change crosses NULL cardinality constraint transaction precision parameter dialect or DDL boundary whose semantics remain unclear | Current SQL row contracts engine behavior and focused fixtures settle the changed boundary | task-agent, analysis-agent, review-agent | option-comparison, selected-approach |