PHP is safe. I want to ask, what should I do if I receive user data?

PHP is safe. I 'd like to ask, how do I handle user data? PHP is safe. I 'd like to ask, how do I handle user data? Is there a standard common receiving function? Now it is basically: $ a =$ _ POST [& quot; a & quot;]; or $ a =$ _ GET [& quot; a & quot;]; how do I receive it? Or how do I say PHP Security? I want to ask, how do I handle user data?
PHP is safe. I 'd like to ask, how do I handle user data? Is there a standard common receiving function?

Now it's basically all:
$ A = $ _ POST ["a"];
Or
$ A = $ _ GET ["a"];

How do I receive it? Or how can I filter the data to make it safer? Because the SQL statement is executed. How to ensure security?

It is better to have a comprehensive function to process these requests.
1. special characters can be filtered to prevent SQL injection.
2. data such as POST, GET, COOKIE, and REQUEST can be received.

Do you have any questions to share?

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Use the extract () function?
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Discussion

Use the extract () function?