Se connecter depuis .NET, Rust et le reste

Host=db.exemple.fr;Port=5432;Database=app;Username=app_api;Password=...;SSL Mode=VerifyFull;
Maximum Pool Size=20;Timeout=15;Command Timeout=30

// Enregistrer un NpgsqlDataSource : il gère le pool
builder.Services.AddNpgsqlDataSource(connectionString);

app.MapGet("/clients/{id:long}", async (long id, NpgsqlDataSource db, CancellationToken ct) =>
{
    await using var cmd = db.CreateCommand("SELECT id, nom FROM clients WHERE id = $1");
    cmd.Parameters.AddWithValue(id);
    await using var reader = await cmd.ExecuteReaderAsync(ct);
    return await reader.ReadAsync(ct) ? Results.Ok(new { Id = reader.GetInt64(0), Nom = reader.GetString(1) })
                                       : Results.NotFound();
});

// Avec EF Core : options.UseNpgsql(connectionString)

let pool = sqlx::postgres::PgPoolOptions::new()
    .max_connections(20)
    .connect(&std::env::var("DATABASE_URL")?)
    .await?;

let client = sqlx::query!("SELECT id, nom FROM clients WHERE id = $1", 42_i64)
    .fetch_optional(&pool)
    .await?;