diesel

[![diesel logo](https://diesel.rs/assets/images/diesel_logo_stacked_black.png)](https://diesel.rs)

# A safe, extensible ORM and Query Builder for Rust

[![Build Status](https://github.com/diesel-rs/diesel/workflows/CI%20Tests/badge.svg)](https://github.com/diesel-rs/diesel/actions?query=workflow%3A%22CI+Tests%22+branch%3Amain)
[![Crates.io](https://img.shields.io/crates/v/diesel.svg)](https://crates.io/crates/diesel)

API Documentation: [latest release](https://docs.rs/diesel) – [main branch](https://docs.diesel.rs/main/diesel/index.html)

[Homepage](https://diesel.rs)

Diesel gets rid of the boilerplate for database interaction and eliminates
runtime errors without sacrificing performance. It takes full advantage of
Rust's type system to create a low overhead query builder that "feels like
Rust."

Supported databases:
1. [PostgreSQL](https://docs.diesel.rs/main/diesel/pg/index.html)
2. [MySQL](https://docs.diesel.rs/main/diesel/mysql/index.html)
3. [SQLite](https://docs.diesel.rs/main/diesel/sqlite/index.html)
4. [MariaDB](https://docs.diesel.rs/main/diesel/mariadb/index.html)

You can configure the database backend in `Cargo.toml`:

```toml
[dependencies]
diesel = { version = "<version>", features = ["<postgres|mysql|sqlite>"] }
```

## Getting Started

Find our extensive Getting Started tutorial at
[https://diesel.rs/guides/getting-started](https://diesel.rs/guides/getting-started).
Guides on more specific features are coming soon.

## Getting help

If you run into problems, you can come ask for help at in our [GitHub Discussions](https://github.com/diesel-rs/diesel/discussions) forum. 
This is also the right place to propose new features or show your applications.

## Usage

### Simple queries

Simple queries are a complete breeze. Loading all users from a database:

```rust
users::table.load(&mut connection)
```

Executed SQL:

```sql
SELECT * FROM users;
```

Loading all the posts for a user:

``` rust
Post::belonging_to(user).load(&mut connection)
```

Executed SQL:

```sql
SELECT * FROM posts WHERE user_id = 1;
```

### Complex queries

Diesel's powerful query builder helps you construct queries as simple or complex as
you need, at zero cost.

```rust
let versions = Version::belonging_to(krate)
  .select(id)
  .order(num.desc())
  .limit(5);
let downloads = version_downloads
  .filter(date.gt(now - 90.days()))
  .filter(version_id.eq_any(versions))
  .order(date)
  .load::<Download>(&mut conn)?;
```

Executed SQL:

```sql
SELECT version_downloads.* FROM version_downloads
  WHERE date > (NOW() - '90 days')
    AND version_id = ANY(
      SELECT id FROM versions
        WHERE crate_id = 1
        ORDER BY num DESC
        LIMIT 5
    )
  ORDER BY date
```

### Less boilerplate

Diesel codegen generates boilerplate for you. It lets you focus on your business logic, not mapping to and from SQL rows.

That means you can write this:

```rust
#[derive(Queryable, Selectable)]
#[diesel(table_name = downloads)]
pub struct Download {
    id: i32,