What are some best practices for debugging PHP code that involves SQL queries?

When debugging PHP code that involves SQL queries, it is important to echo or log the SQL query being executed to ensure it is correct. Additionally, check for any errors returned by the SQL query execution to pinpoint the issue. Utilizing tools like var_dump() or print_r() to inspect the data being retrieved from the database can also be helpful. 

// Example of debugging PHP code with SQL queries
$sql = "SELECT * FROM users WHERE id = $user_id";
echo $sql; // Output the SQL query being executed

$result = mysqli_query($conn, $sql);
if (!$result) {
    die('Error: ' . mysqli_error($conn)); // Check for SQL query execution errors
}

while ($row = mysqli_fetch_assoc($result)) {
    var_dump($row); // Inspect the data retrieved from the database
}

Keywords

MySQL PDO SQL injection error handling debugging

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