> For the complete documentation index, see [llms.txt](https://azutopia.gitbook.io/cql/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://azutopia.gitbook.io/cql/readme.md).

# CQL Documentation

A type-safe query builder and Active Record ORM for Crystal on SQLite, PostgreSQL, MySQL and CockroachDB.

Schemas, models and queries are Crystal code, so a misspelled column or a value of the wrong type fails at compile time, and every value reaches the database as a bound parameter. CQL ships its own PostgreSQL driver.

```crystal
require "cql"
require "sqlite3"

AppDB = CQL::Schema.define(:app, adapter: CQL::Adapter::SQLite, uri: "sqlite3://./app.db") do
  table :users do
    primary :id, Int64, auto_increment: true
    text :name
  end
end

class User
  include CQL::ActiveRecord::Model(Int64)
  db_context AppDB, :users
  property name : String

  def initialize(@name : String)
  end
end

AppDB.users.create!
User.create!(name: "Ada")
User.where(name: "Ada").count # => 1   SELECT COUNT(*) FROM users WHERE users.name = ?
```

## Start Here

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Installation</strong></td><td>Add the shards for your database and check the connection.</td><td><a href="/cql/installation.md">Installation</a></td></tr><tr><td><strong>Tutorials</strong></td><td>Learn CQL step by step, from a first app to a full blog.</td><td><a href="/cql/tutorials/tutorials.md">Tutorials Overview</a></td></tr><tr><td><strong>How-to Guides</strong></td><td>One task per page: models, queries, migrations, caching, PostgreSQL.</td><td><a href="/cql/how-to-guides/how-to.md">How-to Overview</a></td></tr><tr><td><strong>Reference</strong></td><td>Every setting, DSL method, callback, validator and error.</td><td><a href="/cql/reference/reference.md">Reference Overview</a></td></tr><tr><td><strong>Explanation</strong></td><td>How CQL works and why: Active Record, guardrails, performance.</td><td><a href="/cql/explanation/explanation.md">Explanation Overview</a></td></tr><tr><td><strong>Resources</strong></td><td>FAQ and how to contribute.</td><td><a href="/cql/resources/resources.md">Resources Overview</a></td></tr></tbody></table>

Source, issues and releases: [azutoolkit/cql](https://github.com/azutoolkit/cql) on GitHub. CQL is available under the MIT license.


---

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