What potential issues could arise when using MySQL queries in PHP?

One potential issue that could arise when using MySQL queries in PHP is SQL injection attacks if user input is not properly sanitized. To prevent this, you should always use prepared statements or parameterized queries to bind user input data to query parameters. This helps to protect against malicious SQL injection attacks by separating SQL code from user input data. 

// Using prepared statements to prevent SQL injection
$mysqli = new mysqli("localhost", "username", "password", "database");

// Check connection
if ($mysqli->connect_error) {
    die("Connection failed: " . $mysqli->connect_error);
}

// Prepare a SQL query with a placeholder for user input
$stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username);

// Set the user input data and execute the query
$username = $_POST['username'];
$stmt->execute();

// Process the results
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
    // Do something with the data
}

// Close the statement and connection
$stmt->close();
$mysqli->close();

Keywords

MySQL PHP SQL injection error handling database connectivity

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