PHP is a widely used open source programming language powering the majority of the websites on the internet - including platforms like WordPress and Magento. The W3 Schools certification ensures the fundamental knowledge of PHP & SQL.
There are many ways to tackle a requirement with PHP. Knowing all the functions ensures the code is written in the best way.
PHP isn't static. It is frequently updated and can produce different results depending on the server environment. The exam goes over possible error messages and what they mean.
The SQL portion of the exam goes over data types and other database fundamentals, ensuring the proper usage and storage of data.
PHP and all coding languages have security loopholes. The exam goes over the popular ones so we know what to avoid while writing code.