SQL Skill Pack

A new SQL Skill Pack from an unnamed course teaches building two validator skills: sql-migration-safety-check, which flags destructive migration patterns like dropped columns and unindexed foreign keys, and sql-query-review, which catches missing WHERE clauses, SELECT *, and N+1 patterns. The pack emphasizes strict failure handling to prevent softening blocking findings.

· Agentic AI · 5 min read 📋 Prerequisites - Python Skill Pack previous lesson 🎯 What You'll Learn - Build a Validator skill that catches destructive or unsafe migration patterns before they run - Build a Reviewer skill that checks query safety and performance against real anti-patterns - Design failure handling for a skill that could recommend a genuinely destructive action What This Pack Covers Two skills: one that checks database migrations for destructive or risky changes before they run, and one that reviews hand-written queries for correctness and performance issues. Both deal with actions that are expensive or dangerous to get wrong, which makes the failure-handling discipline from Skill Engineering /courses/production-agent-skills-engineering/skill-engineering-fundamentals especially relevant here. Skill 1: sql-migration-safety-check --- name: sql-migration-safety-check description: Reviews a SQL migration file for destructive or risky changes before it runs — dropped columns, missing defaults on new NOT NULL columns, and lock-heavy operations on large tables. Use when reviewing a migration, before running one against production, or when the user asks if a migration is safe. metadata: version: "1.0.0" --- Constraints Never state a migration is "safe" without checking every rule below. When uncertain about a table's size or production usage, say so explicitly rather than assuming it's small. Review checklist 1. Dropped columns or tables. Flag any DROP COLUMN or DROP TABLE — these are irreversible without a backup. Confirm a rollback plan exists before calling this acceptable. 2. NOT NULL without a default. Adding a NOT NULL column to an existing table without a DEFAULT will fail on any table with existing rows. Flag this as a blocking issue, not a suggestion. 3. Unindexed foreign keys. A new foreign key column without an accompanying index will cause slow joins and slow cascade deletes as the table grows. 4. Lock-heavy operations on large tables. ALTER TABLE operations that rewrite an entire table adding a column with a non-null default on most database engines, for example lock the table for the duration. Flag this and suggest a safer, phased approach when possible — add the column nullable first, backfill, then add the constraint separately. On failure If any blocking issue is found, do not soften the assessment — state clearly that the migration should not run as written, and what needs to change first. Pattern: Validator, with an explicit constraint from Skill Engineering /courses/production-agent-skills-engineering/skill-engineering-fundamentals against the failure mode that matters most here — a validator that’s been talked into softening a genuinely blocking finding is worse than no validator at all. Skill 2: sql-query-review --- name: sql-query-review description: Reviews a SQL query for correctness and performance issues — missing WHERE clauses on UPDATE/DELETE, SELECT , and likely N+1 query patterns. Use when reviewing a query before it ships, or when the user asks whether a query is safe or efficient. metadata: version: "1.0.0" --- Review checklist 1. UPDATE or DELETE without a WHERE clause. This is the single highest- severity finding this skill can report — flag it first, ahead of every other check, and state plainly what rows would be affected all of them . 2. SELECT \ . Flag in application code fine in ad-hoc exploration, not in code that ships — it breaks when columns are added later and pulls more data than needed. 3. Queries inside a loop. If the surrounding code shows a query being constructed or executed inside a loop over application-level records, flag this as a likely N+1 pattern and suggest a single batched query or a join instead. 4. Unparameterized string-built queries. Any query built via string concatenation or f-strings with user input inserted directly is a SQL injection risk — flag this as blocking, not a style note. Report findings ordered by severity: missing WHERE clause and injection risk first, then performance issues. Pattern: Reviewer — assessing already-written SQL against criteria and reporting specific, prioritized findings, per Skill Design Patterns /courses/production-agent-skills-engineering/skill-design-patterns . Why Severity Ordering Matters Here Both skills above explicitly order their findings by severity rather than just listing checks in an arbitrary sequence. This matters more for a SQL pack than for most: a missing WHERE clause on a DELETE is catastrophic and a SELECT is a minor style issue, and a skill that reports them with equal visual weight risks a genuinely dangerous finding getting lost among cosmetic ones. This is worth checking specifically during testing — not just whether a skill catches every issue, but whether the most dangerous one is impossible to miss in its output. Testing Both Skills Run sql-migration-safety-check against a migration with no issues, one with exactly one blocking issue a DROP COLUMN , and one with several issues at different severities — confirm the blocking issue is never softened into a mere suggestion. Run sql-query-review against a query that’s genuinely fine, one with an unqualified DELETE , and one with a plausible N+1 pattern in the surrounding code — this last case is the hardest to get reliably right, since it depends on the skill reading context beyond just the query text itself, and is worth testing with a real code snippet, not just the bare SQL. Summary sql-migration-safety-check is a Validator focused on irreversible or lock-heavy changes, with an explicit constraint against softening a blocking finding sql-query-review is a Reviewer covering correctness missing WHERE, injection risk and performance SELECT , N+1 patterns , ordered by severity- Both skills deal with genuinely destructive or risky actions, which is exactly the case Skill Engineering /courses/production-agent-skills-engineering/skill-engineering-fundamentals says warrants explicit, non-negotiable constraints rather than soft suggestions - Test not just whether each skill catches every issue, but whether the most severe one is impossible to miss in the output Next, a pack for the collaboration layer around code — pull requests, issue triage, and release notes, using the GitHub CLI.