Db - Introduction

The Db class is a wrapper around the PHP Data Objects (PDO) extension and serves as a database abstraction layer to provide a simple, consistent interface for interacting with different types of databases.

It is designed to use procedural methods and is responsible for establishing a connection to the database, executing queries, and returning results. The Db class uses a DriverBase instance for the connection and a QueryBuilder instance for building and executing SQL queries.

In summary, the Db class provides a procedural interface for executing SQL queries and managing the database connection, while the QueryBuilder class provides a fluent interface for building SQL queries.

Instantiating the Db class

The Db class is instantiated using Dependency Injection (DI) via the bootstrap.php file. Here's an example of how to do it:

use Migliori\PowerLitePdo\Db;

$container = require_once __DIR__ . '/../src/bootstrap.php';
$db = $container->get(Db::class);

This code first includes the bootstrap.php file, which sets up the DI container. Then, it retrieves an instance of the Db class from the container.

Accessing the PDO child object

The Db class has a protected property $pdo that holds the PDO instance. This PDO instance is used to execute queries against the database. Here's an example of how to retrieve the PDO instance:

$pdo = $db->getPdo();

This code calls the getPdo() method on the Db instance to retrieve the PDO instance.

Accessing the Query Builder child object

The Db class also has a protected property $queryBuilder that holds an instance of the Query Builder. The Query Builder provides a fluent interface to build SQL queries.

If you ever need to switch to using the Query Builder instance and utilize its fluent style instead of the Db class methods for constructing your queries, here's how you can proceed:

$queryBuilder = $db->getQueryBuilder();

This code calls the getQueryBuilder() method on the Db instance to retrieve the Query Builder instance.

PDO Driver Manager

The DriverManager class is responsible for managing the PDO drivers. It provides a method to get the appropriate driver based on the database type. The DriverManager class is used internally by the Db class to manage the PDO connection. You can find more details about the DriverManager class in the DriverManager.php file.