Learn PHP Programming: Connecting to SQL, Querying Databases, and Displaying Arrays
In this beginner-friendly online lesson, you'll learn how to connect to SQL using PHP, perform queries on a database, and display arrays on the screen. With examples and easy-to-follow code snippets, this lesson will guide you through the fundamentals of PHP programming and empower you to build dynamic web pages and web applications. Whether you're a seasoned developer or just starting, this lesson is a valuable resource for anyone looking to master PHP programming.
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Introduction to PHP Programming
PHP is a popular server-side scripting language that is used to build dynamic web pages and web applications. With PHP, you can easily connect to databases, perform queries, and display data on the screen. In this lesson, we will learn about PHP programming and how to work with databases using PHP.
Connecting to SQL
To connect to a database using PHP, you need to use the PHP Data Objects (PDO) extension. The following code shows how to connect to a MySQL database using PDO.
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
}
catch(PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}
In this code, we are setting the servername, username, password, and dbname variables with the appropriate values. Then, we are creating a new PDO object and passing the connection string as the first argument. The connection string specifies the database host, name, username, and password. Finally, we are setting the error mode to exception and handling any errors that may occur.
Working with a Database
Once you have connected to a database, you can perform various operations on it. The following code shows how to create a new table in a database using PDO.
$sql = "CREATE TABLE users (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)";
$conn->exec($sql);
echo "Table created successfully";
In this code, we are creating a new table called "users" with several columns. The id column is set to auto-increment and is used as the primary key. The firstname and lastname columns are set to not null, and the email column is optional. Finally, we are setting the reg_date column to the current timestamp.
Queries to the Database
Once you have created a table, you can perform various queries on it. The following code shows how to insert data into a table using PDO.
$sql = "INSERT INTO users (firstname, lastname, email)
VALUES ('John', 'Doe', '[email protected]')";
$conn->exec($sql);
echo "Record created successfully";
In this code, we are inserting a new record into the users table with the firstname, lastname, and email values.
Displaying Arrays on the Screen
Once you have retrieved data from the database, you can display it on the screen. The following code shows how to retrieve data from a table and display it on the screen using PDO.
$sql = "SELECT id, firstname, lastname, email FROM users";
$result = $conn->query($sql);
if ($result->rowCount() > 0) {
while($row = $result->fetch()) {
echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. " - Email: " . $row["email"]. "<br>";
}
} else {
echo "0 results";
}
In this code, we are selecting all the data from the users table and using a while loop to iterate.
This online lesson provides a beginner-friendly guide to PHP programming, covering topics such as connecting to SQL, querying databases, and displaying arrays on the screen. With examples and easy-to-follow code snippets, learners can gain fundamental skills in PHP programming, enabling them to build dynamic web pages and web applications.
