Json_decode. Error adding to database?

Question

PHP

Problem adding to database.
There is a form that works on Ajax Json PHP. I use json_decode, an error occurs when adding to the database.
Initially it didn't work with adding text in double quotes, I solved the problem like this:
$value = str_replace("\"", "", $value);
$value = str_replace('\\', '/', $value);
$ value = preg_replace('#(\.|\?|!|\(|\)){3,}#', '\1', $value);
Now everything works fine, but when entering the "&" sign into the field an error occurs when adding to the database
Please help!

Answer 1

Initially did not work with adding text in double quotes

Don't shoot yourself in the head, use mysqli_real_escape_string() or PDO, that's what they are for.
Because such regular expressions are a highway for SQL injections.

Answer 2

See mysqli_real_escape_string