Rust: sqlx

Connects, creates a todo table if it does not exist, inserts a row and counts open rows. The code is the same against the original database and against MachSQL; only the address changes.

The only change

DATABASE_URL=postgres://app:${DB_PASSWORD}@old-postgres:5432/app
DATABASE_URL=postgres://app:${DB_PASSWORD}@machsql-host:5432/app

Nothing else changes: not the code, not the driver, not its version, not the SQL.

Versions

• Rust (latest stable, edition 2024)
• sqlx 0.9.0
• tokio 1.54.1

Run

export DATABASE_URL=postgres://app:${DB_PASSWORD}@machsql-host:5432/app
cargo run

Expected output: inserted todo <id>, <n> open.

Source

The program as it is kept and tested in the Mach Database for PostgreSQL repository; highlighted lines read the connection setting.

src/main.rs

//! sqlx with a PostgreSQL connection pool.

#[tokio::main]
async fn main() -> Result<(), sqlx::Error> {
    let url = std::env::var("DATABASE_URL").expect("set DATABASE_URL");
    let pool = sqlx::PgPool::connect(&url).await?;
    sqlx::query("CREATE TABLE IF NOT EXISTS todo (id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY, title text NOT NULL, done boolean NOT NULL DEFAULT false)")
        .execute(&pool)
        .await?;
    let id: i64 = sqlx::query_scalar("INSERT INTO todo (title) VALUES ($1) RETURNING id")
        .bind("write the examples")
        .fetch_one(&pool)
        .await?;
    let open: i64 = sqlx::query_scalar("SELECT count(*) FROM todo WHERE NOT done")
        .fetch_one(&pool)
        .await?;
    println!("inserted todo {id}, {open} open");
    Ok(())
}

Cargo.toml

[package]
name = "machsql-example-sqlx"
version = "0.1.0"
edition = "2024"
publish = false

# Not a member of the MachSQL workspace.
[workspace]

[dependencies]
sqlx = { version = "0.9.0", default-features = false, features = ["runtime-tokio", "tls-rustls", "postgres", "macros"] }
tokio = { version = "1.54.1", features = ["macros", "rt-multi-thread"] }