Why does this SQL UPDATE query not work with a variable for WHERE?

Question

this is my first post here at Stack Overflow. I know the question has been asked many times before. I went through many answers, tried all of them (except the correct approa

Answer 1

The following query can be used:

UPDATE VideoArchiv SET columnname1 = '".$_POST["titel"]."', columnname2 = '".$_POST["schauspieler"]."' WHERE id=$id