What is the difference between mysql_connect and mysqli_query in PHP and how does it affect database operations?

The main difference between mysql_connect and mysqli_query in PHP is that mysql_connect is deprecated as of PHP 5.5.0 and removed in PHP 7.0.0, while mysqli_query is the recommended way to interact with MySQL databases in PHP. Using mysqli_query ensures better security, performance, and support for newer MySQL features. To fix this issue, you should switch from using mysql_connect to mysqli_query in your PHP code.

// Using mysqli_connect to establish a connection to the MySQL database
$mysqli = mysqli_connect("localhost", "username", "password", "database");

// Using mysqli_query to execute a SQL query
$result = mysqli_query($mysqli, "SELECT * FROM table");

// Loop through the results
while ($row = mysqli_fetch_assoc($result)) {
    // Process data here
}

// Close the database connection
mysqli_close($mysqli);