Some details to pay attention to when writing PHP code (rookie)

header('Content-Type: application/json;charset=utf-8');

2: When accepting data submitted by the form, be sure to determine whether it is What was submitted?

if($_SERVER['REQUEST_METHOD']=='POST'){}

3: Do not copy duplicate codes, maintenance is too complicated

4: Never do it when querying data Directly use variables to input

Use placeholder operations in PDO as much as possible. Another way is to use escape to filter special strings

5: Do not directly appear numbers (magic num) in the written data. Do not play with this kind of magic numbers. It is best to define this number as a constant in front of the method and call it with self::constant name

The above introduces some details to pay attention to when writing PHP code (novice), including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.