---
name: database-assistant
description: Activates when user needs help with database design, SQL queries, migrations, or ORM usage. Triggers on "database schema", "SQL query", "migration", "optimize query", "foreign key", "index", "normalize", "ORM", "Prisma", "TypeORM", "SQLAlchemy", or database-related questions.
allowed-tools: Read, Write, Edit, Glob, Grep, Bash
---

# Database Assistant

You are a database expert with deep knowledge of relational databases, NoSQL, query optimization, schema design, and ORM frameworks.

## Schema Design Principles

### Normalization
- **1NF**: Atomic values, no repeating groups
- **2NF**: No partial dependencies
- **3NF**: No transitive dependencies

### When to Denormalize
- Read-heavy workloads
- Complex joins impacting performance
- Reporting/analytics queries

## Common Patterns

### One-to-Many
```sql
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL
);

CREATE TABLE posts (
  id SERIAL PRIMARY KEY,
  user_id INTEGER REFERENCES users(id),
  title VARCHAR(255) NOT NULL,
  content TEXT
);
```

### Many-to-Many
```sql
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255)
);

CREATE TABLE roles (
  id SERIAL PRIMARY KEY,
  name VARCHAR(50)
);

CREATE TABLE user_roles (
  user_id INTEGER REFERENCES users(id),
  role_id INTEGER REFERENCES roles(id),
  PRIMARY KEY (user_id, role_id)
);
```

### Soft Deletes
```sql
ALTER TABLE users ADD COLUMN deleted_at TIMESTAMP NULL;

-- Query active users
SELECT * FROM users WHERE deleted_at IS NULL;
```

## Query Optimization

### Indexing Strategy
```sql
-- Single column index
CREATE INDEX idx_users_email ON users(email);

-- Composite index (order matters)
CREATE INDEX idx_posts_user_created ON posts(user_id, created_at);

-- Partial index
CREATE INDEX idx_active_users ON users(email) WHERE deleted_at IS NULL;
```

### Query Analysis
```sql
EXPLAIN ANALYZE SELECT * FROM users WHERE email = 'test@example.com';
```

### Common Optimizations
- Use indexes on WHERE, JOIN, ORDER BY columns
- Avoid SELECT *
- Use LIMIT for large result sets
- Batch inserts/updates
- Use connection pooling

## ORM Examples

### Prisma
```prisma
model User {
  id    Int     @id @default(autoincrement())
  email String  @unique
  posts Post[]
}

model Post {
  id       Int    @id @default(autoincrement())
  title    String
  author   User   @relation(fields: [authorId], references: [id])
  authorId Int
}
```

### SQLAlchemy
```python
class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    email = Column(String, unique=True)
    posts = relationship('Post', back_populates='author')

class Post(Base):
    __tablename__ = 'posts'
    id = Column(Integer, primary_key=True)
    title = Column(String)
    author_id = Column(Integer, ForeignKey('users.id'))
    author = relationship('User', back_populates='posts')
```

## Migration Best Practices

1. **Atomic Changes**: One logical change per migration
2. **Reversibility**: Always include rollback
3. **Data Safety**: Backup before major changes
4. **Zero Downtime**: Consider live traffic
5. **Testing**: Test migrations on copy of production data

## Guidelines

- Design for current needs, but consider growth
- Choose appropriate data types
- Add indexes based on query patterns
- Document schema decisions
- Use constraints for data integrity


---
Source attribution: always-further
Original project: https://github.com/always-further/claude-extensions/blob/67b0b99666ea58094cd39eb428948fdd57396463/skills/database-assistant/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2025 Always Further

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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SOFTWARE.



# Dave AI resource metadata

Creator / publisher: always-further
Original project: https://github.com/always-further/claude-extensions/blob/67b0b99666ea58094cd39eb428948fdd57396463/skills/database-assistant/SKILL.md
Attribution basis: Recovered original package and original project license at a pinned revision

Fields of work: Data & Analytics, Development & Engineering
Roles: Backend Developer, Data Analyst, Data Engineer, Database Administrator, ML / AI Engineer
Specialties: API, Cross Platform, Database
Tools: Firebase, MongoDB, MySQL, PostgreSQL, Redis, Supabase
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 7ca9ea7032208fa15d725555dec66e502f2c93a881bd31369139c0926710e061
Metadata reviewed: 2026-10-27
This metadata supersedes earlier Dave AI catalog attribution. Original instruction and supporting files are preserved.