# Sqlite Data

> Use when working with SQLiteData library (@Table, @FetchAll, @FetchOne macros) for SQLite persistence, queries, writes, migrations, or CloudKit private database sync.

- Skill: `majiayu000/sqlite-data` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/sqlite-data`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/sqlite-data/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/sqlite-data

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# SQLite Data

SQLiteData provides type-safe SQLite access through Swift macros, simplifying database modeling and queries while handling CloudKit sync, migrations, and async patterns automatically.

## Overview

## Quick Reference

| Reference | Load When |
|-----------|-----------|
| **[Table Models](references/models.md)** | Defining database tables with `@Table` macro, setting up primary keys, columns, or enums |
| **[Queries](references/queries.md)** | Using `@FetchAll`, `@FetchOne`, `@Fetch` property wrappers, or building queries with joins/filters |
| **[Writes](references/writes.md)** | Inserting, updating, upserting, or deleting records; managing transactions |
| **[Views](references/views.md)** | Integrating `@FetchAll`/`@FetchOne` with SwiftUI views, `@Observable` models, UIKit, or TCA `@ObservableState` |
| **[Migrations](references/migrations.md)** | Creating database migrations with DatabaseMigrator or `#sql()` macro |
| **[CloudKit Sync](references/cloudkit.md)** | Setting up CloudKit private database sync, sharing, or sync delegates |
| **[Dependencies](references/dependencies.md)** | Injecting database/sync engine via `@Dependency`, bootstrap patterns, or TCA integration |
| **[Testing](references/testing.md)** | Setting up test databases, seeding data, or writing assertions for SQLite code |
| **[Advanced](references/advanced.md)** | Implementing triggers, full-text search (FTS5), or custom database functions |
| **[Schema Composition](references/schema-composition.md)** | Using @Selection column groups, single-table inheritance, or database views |

## Core Workflow

When working with SQLiteData:
1. Define table models with `@Table` macro
2. Use `@FetchAll`/`@FetchOne` property wrappers in views or `@Observable` models
3. Access database via `@Dependency(\.defaultDatabase)`
4. Perform writes in `database.write { }` transactions
5. Set up migrations before first use

## Common Mistakes

1. **N+1 query patterns** — Loading records one-by-one in a loop (e.g., fetching user then fetching all their posts separately) kills performance. Use joins or batch fetches instead.

2. **Missing migrations on schema changes** — Modifying `@Table` without creating a migration causes crashes at runtime. Always create migrations for schema changes before deploying.

3. **Improper transaction handling** — Long-running transactions outside of `database.write { }` block can cause deadlocks or data loss. Keep write blocks short and focused.

4. **Ignoring CloudKit sync delegates** — Setting up CloudKit sync without implementing `SyncDelegate` means you miss error handling and conflict resolution. Implement all delegate methods for production.

5. **Over-fetching in SwiftUI views** — Using `@FetchAll` without filtering/limiting can load thousands of records, freezing the UI. Use predicates, limits, and sorting to keep in-memory footprint small.