如何从PHP中的sql获取最大值

Question

So I'm buidlign a website currently and there is a form connected to a database.

You can put some information in the form and it will send you an email and will put the information into the database.

So... I wanted it also ad a number into the database and auto count the number. This lead me thinking.... If I use max and just do +1 and insert that, Jobs done right!!.... Well no....

The code isn't working for me and I have no idea where to start...

This is al I made and when I do this I only get 1 as an answer.

$sql2 = "SELECT MAX(Nummer) FROM Leerling" ;
$sql3 = $sql2 + 1;

echo $sql3;

The insert statement is

"INSERT INTO Leerling(Nummer, Naam, Klas, Email, Bericht) VALUES ('" . $sql3 . "', '" .$naam. "', '" .$klas. "' , '" .$email. "', '" .$bericht. "');" ;

Which only inserts 0 into the database on the place where it says $sql2. I'm totaly clueless so any help is much needed help.

(Don't mind my English if it's not correct >.< I'm Dutch)

Answer 1

You should use MySQL AUTO_INCREMENT

Your column Nummer will increase its value every time you insert a new row and no need for calculate the MAX value to increase Nummer for the new row