What are the best practices for debugging SQL queries in PHP applications?

When debugging SQL queries in PHP applications, it is important to echo or log the SQL query being executed along with any relevant variables to ensure that the query is being constructed correctly. Additionally, using error handling functions such as mysqli_error() or PDOException can help identify any errors in the query execution. Finally, utilizing tools like phpMyAdmin or MySQL Workbench to run and test queries separately can also aid in debugging.

// Example of debugging SQL queries in PHP

$query = "SELECT * FROM users WHERE id = $user_id";
echo "Query: " . $query; // Output the query being executed

$result = mysqli_query($connection, $query);
if (!$result) {
    die("Error: " . mysqli_error($connection)); // Display any errors in query execution
}

// Process the query result here