In the provided PHP script, what potential pitfalls or errors could arise from using functions like sql_fetch_row() without proper definition?

When using functions like sql_fetch_row() without proper definition, potential pitfalls include undefined function errors, unexpected behavior, and security vulnerabilities. To solve this issue, make sure to define or include the necessary functions before calling them in the script.

// Include the necessary file or define the function before using it
include 'db_connection.php';

// Use the defined function to fetch a row from the database
$row = sql_fetch_row($result);