AgentSkillsCN

database

定义数据库与持久化规则：原始SQL的使用、仓库边界、事务处理、迁移操作。在编写仓库、SQL查询，或进行迁移时使用。

SKILL.md
--- frontmatter
name: database
description: Defines database and persistence rules: raw SQL usage, repository boundaries, transactions, migrations. Use when writing repositories, SQL queries, or migrations.

Database & Repositories

The database layer is responsible for data persistence only. It must remain explicit, auditable, and predictable.

Stack

  • •MySQL
  • •Raw SQL with named parameters
  • •No ORM (performance and control first)

Core Rules

  • •SQL is allowed only inside repositories
  • •No database access outside repositories
  • •Repositories must not contain business logic
  • •Domain and services must be database-agnostic

Architectural violations are treated as bugs.

SQL Standards

  • •Explicit column selection is mandatory (SELECT * is forbidden)
  • •Named parameters are required
  • •No dynamic SQL string concatenation
  • •Queries must be readable, formatted, and auditable

Rules:

  • •No implicit joins
  • •Joins must be explicit and justified
  • •Subqueries must remain readable

Repository Responsibilities

Repositories may:

  • •Execute SQL queries
  • •Map rows to data structures
  • •Support transactional contexts

Repositories must not:

  • •Make business decisions
  • •Contain validation rules
  • •Manage transactions autonomously

Transactions

  • •Transaction boundaries are defined at the service layer
  • •Repositories must support receiving a transactional context
  • •Nested transactions are forbidden unless explicitly supported

Rules:

  • •No implicit transactions
  • •No auto-commit logic in repositories
  • •Transaction intent must be explicit in services

Migrations

  • •Migrations are SQL-only files
  • •Migrations are immutable once applied
  • •One logical change per migration

Rules:

  • •No data + schema changes in the same migration
  • •Migrations must be reversible when possible
  • •Migration names must describe intent clearly

Performance Guidelines

  • •Queries must be index-aware
  • •Avoid N+1 query patterns
  • •Measure before optimizing

Rules:

  • •No speculative indexes
  • •Index changes require justification
  • •Large queries must be reviewed with EXPLAIN when relevant

Data Integrity

  • •Enforce constraints at the database level where possible
  • •Prefer NOT NULL, UNIQUE, and FOREIGN KEY constraints
  • •Do not rely solely on application-level validation

Security Rules

  • •Always use parameterized queries
  • •Never interpolate user input into SQL
  • •Database credentials must remain server-side

Testing Expectations

  • •Repositories must be testable in isolation
  • •Critical queries must be covered
  • •Edge cases (empty results, constraints) must be explicit

Non-Negotiables

  • •No ORM
  • •No SELECT *
  • •No dynamic SQL
  • •No business logic in repositories

Predictability over convenience.
The database is a critical system boundary.