DatabaseHandler Class Documentation

The DatabaseHandler class provides a secure and easy-to-use interface for interacting with a MySQL database in PHP. It handles database connections, CRUD (Create, Read, Update, Delete) operations, data sanitization, and basic data validation.

Constructor

__construct($host, $username, $password, $database)

• Description: Initializes a new DatabaseHandler object and establishes a connection to the MySQL database.
• Parameters:
  • $host: The hostname of the database server.
  • $username: The username used to connect to the database.
  • $password: The password used to connect to the database.
  • $database: The name of the database to connect to.
• Returns: None.

Methods

insertData($table, $data)

• Description: Inserts data into the specified table in the database.
• Parameters:
  • $table: The name of the table where the data will be inserted.
  • $data: An associative array containing the column names and values to be inserted.
• Returns: true if the data is successfully inserted, otherwise returns an error message string.

Example:

$db = new DatabaseHandler("localhost", "username", "password", "database");

$data = array(
    "name" => "John",
    "email" => "john@example.com"
);

$result = $db->insertData("users", $data);
if ($result === true) {
    echo "Data inserted successfully.";
} else {
    echo "Error: " . $result;
}

readData($table, $conditions = "")

Description: Reads data from the specified table in the database.

Parameters:

• $table: The name of the table from which data will be read.
• $conditions (optional): Additional conditions to filter the data (e.g., WHERE clause).

Returns: An array containing the retrieved data as associative arrays, or an error message string if an error occurs.

Example:

$db = new DatabaseHandler("localhost", "username", "password", "database");

$users = $db->readData("users");
if (!is_string($users)) {
    foreach ($users as $user) {
        echo "Name: " . $user['name'] . ", Email: " . $user['email'] . "<br>";
    }
} else {
    echo "Error: " . $users;
}

readData($table, $conditions = "")

Description: Reads data from the specified table in the database.

Parameters:

• $table: The name of the table from which data will be read.
• $conditions (optional): Additional conditions to filter the data (e.g., WHERE clause).

Returns: An array containing the retrieved data as associative arrays, or an error message string if an error occurs.

Example:

$db = new DatabaseHandler("localhost", "username", "password", "database");

$users = $db->readData("users");
if (!is_string($users)) {
    foreach ($users as $user) {
        echo "Name: " . $user['name'] . ", Email: " . $user['email'] . "<br>";
    }
} else {
    echo "Error: " . $users;
}

updateData($table, $data, $conditions)

Description: Updates data in the specified table in the database.

Parameters:

$table: The name of the table where the data will be updated. $data: An associative array containing the column names and new values. $conditions: Conditions to specify which rows to update (e.g., WHERE clause). Returns: true if the data is successfully updated, otherwise returns an error message string.

Example:

$db = new DatabaseHandler("localhost", "username", "password", "database");

$data = array(
    "name" => "Jane",
    "email" => "jane@example.com"
);

$result = $db->updateData("users", $data, "id = 1");
if ($result === true) {
    echo "Data updated successfully.";
} else {
    echo "Error: " . $result;
}

deleteData($table, $conditions)

Description: Deletes data from the specified table in the database.

Parameters:

$table: The name of the table from which data will be deleted. $conditions: Conditions to specify which rows to delete (e.g., WHERE clause). Returns: true if the data is successfully deleted, otherwise returns an error message string.

Example:

$db = new DatabaseHandler("localhost", "username", "password", "database");

$result = $db->deleteData("users", "id = 1");
if ($result === true) {
    echo "Data deleted successfully.";
} else {
    echo "Error: " . $result;
}