Plasma 
Plasma provides an asynchronous, non-blocking (data access) Database Abstraction Layer. This is the core component, defining common parts and interfaces.
The core component alone does nothing, you need a Plasma driver, which does all the handling of the DBMS.
Plasma does not aim to be a full Database Abstraction Layer. Simulating missing features is not a goal and should never be.
For a list of drivers, see the main repository.
Getting Started
As soon as you have selected a driver, you can install it using composer. For the core, the command is
composer require plasma/core
Each driver has their own dependencies, as such they have to implement a factory, which creates their driver instances correctly. For more information, see the driver project page.
But this is some little pseudo code:
$loop = \React\EventLoop\Factory::create();
$factory = new \SomeGuy\PlasmaDriver\MsSQLFactory($loop);
$client = \Plasma\Client::create($factory, 'root:1234@localhost');
$client->execute('SELECT * FROM `users`', [])
->then(function (\Plasma\QueryResultInterface $result) use ($client) {
// Do something with the query result
// Most likely for a SELECT query,
// it will be a streaming query result
$client->close()->done();
}, function (\Throwable $error) use ($client) {
// Oh no, an error occurred!
echo $error.\PHP_EOL;
$client->close()->done();
});
$loop->run();Cursors
Cursors are a powerful way to get full control over fetching rows. Cursors allow you to control when a row (or multiple) is fetched from the database and allows your application a small memory footprint while fetching millions of rows.
Cursors return a promise and resolve with the row, an array of rows or false (when no more rows).
Since they return a promise, you don't need to depend on events and possibly buffer rows when passing around the result.
When combining cursors with generator coroutines (such as Recoil), you get a powerful tool you already know from PDO.
// Inside a coroutine
/** @var \Plasma\CursorInterface $cursor */
$cursor = yield $client->createReadCursor('SELECT * FROM `my_table`');
while($row = yield $cursor->fetch()) {
// Process row
}Support for cursors depend on the individual drivers.