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PHP & MySQL
$servername = "localhost"; // Specify the server name or IP address
$username = "your_username"; // Specify your MySQL username
$password = "your_password"; // Specify your MySQL password
$database = "your_database"; // Specify the name of the database you want to connect to
// Create a connection object
$connection = new mysqli($servername, $username, $password, $database);
// Check the connection
if ($connection->connect_error) {
die("Connection failed: " . $connection->connect_error);
}
// Connection successful
echo "Connected to MySQL database successfully!";
In this example, replace "localhost", "your_username", "your_password", and "your_database" with the appropriate values for your MySQL server. The mysqli extension provides an object-oriented approach for database connectivity in PHP.
2. Using the PDO extension:
$servername = "localhost"; // Specify the server name or IP address
$username = "your_username"; // Specify your MySQL username
$password = "your_password"; // Specify your MySQL password
$database = "your_database"; // Specify the name of the database you want to connect to
try {
// Create a PDO instance
$connection = new PDO("mysql:host=$servername;dbname=$database", $username, $password);
// Set the PDO error mode to exception
$connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// Connection successful
echo "Connected to MySQL database successfully!";
} catch (PDOException $e) {
// Connection failed
die("Connection failed: " . $e->getMessage());
}
In this example, replace "localhost", "your_username", "your_password", and "your_database" with the appropriate values for your MySQL server. The PDO extension provides a consistent interface for database connectivity and supports multiple database drivers.
Both methods establish a connection to the MySQL database using the provided credentials. You can use the $connection object (in case of mysqli) or the $connection variable (in case of PDO) to execute queries, fetch data, and perform other database operations.
Remember to handle errors appropriately and ensure that the provided credentials are correct and have sufficient privileges to access the specified database.
$sql = "INSERT INTO users (name, email) VALUES ('John Doe', 'john@example.com')";
if ($connection->query($sql) === true) {
echo "Record created successfully.";
} else {
echo "Error: " . $sql . "<br>" . $connection->error;
}
In this example, the SQL statement inserts a new record into the users table with a name and email. If the query executes successfully, it displays a success message; otherwise, it shows the error message.
3. Read (SELECT) Operation: To retrieve records from the database, execute an SQL SELECT statement. Here’s an example:
$sql = "SELECT * FROM users";
$result = $connection->query($sql);
if ($result->num_rows > 0) {
while ($row = $result->fetch_assoc()) {
echo "ID: " . $row["id"] . " - Name: " . $row["name"] . " - Email: " . $row["email"] . "<br>";
}
} else {
echo "No records found.";
}
In this example, the SQL statement selects all records from the users table. The result is retrieved as a result set, and each row is fetched and displayed using a loop.
4. Update (UPDATE) Operation: To update existing records, execute an SQL UPDATE statement. Here’s an example:
$sql = "UPDATE users SET name='Jane Doe' WHERE id=1";
if ($connection->query($sql) === true) {
echo "Record updated successfully.";
} else {
echo "Error: " . $sql . "<br>" . $connection->error;
}
In this example, the SQL statement updates the name of a user with the ID 1. If the query is successful, it displays a success message; otherwise, it shows the error message.
5. Delete (DELETE) Operation: To delete records from the database, execute an SQL DELETE statement. Here’s an example:
$sql = "DELETE FROM users WHERE id=1";
if ($connection->query($sql) === true) {
echo "Record deleted successfully.";
} else {
echo "Error: " . $sql . "<br>" . $connection->error;
}
In this example, the SQL statement deletes the user with the ID 1. If the query executes successfully, it displays a success message; otherwise, it shows the error message.
Remember to handle errors appropriately and adapt the code according to your database schema and requirements.
$query = "SELECT * FROM users";
$result = mysqli_query($connection, $query);
if ($result) {
// Query executed successfully
// Process the result set
while ($row = mysqli_fetch_assoc($result)) {
// Access the retrieved data
echo $row['name'] . "<br>";
}
// Free the result set
mysqli_free_result($result);
} else {
// Query execution failed
echo "Error: " . mysqli_error($connection);
}
In this example, $connection represents the database connection object, and $query contains the SQL query to be executed. The function returns a result set for SELECT queries, which can be processed using functions like mysqli_fetch_assoc() to access the retrieved data.
2. $pdo->query() (PDO extension): With the PDO extension, the $pdo->query() method is used to execute SQL queries. It takes the SQL query as a parameter and returns a PDOStatement object representing the result set. Here’s an example:
$query = "SELECT * FROM users";
$result = $pdo->query($query);
if ($result) {
// Query executed successfully
// Process the result set
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
// Access the retrieved data
echo $row['name'] . "<br>";
}
// Free the result set
$result->closeCursor();
} else {
// Query execution failed
$errorInfo = $pdo->errorInfo();
echo "Error: " . $errorInfo[2];
}
In this example, $pdo represents the PDO connection object, and $query contains the SQL query to be executed. The $result variable holds the result set, which can be processed using methods like fetch() to access the retrieved data.
It’s worth noting that these functions/methods can execute various types of SQL queries, such as SELECT, INSERT, UPDATE, DELETE, and more. Handle errors appropriately and adapt the code based on your specific use case and database requirements.
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