I have a table with the following fields: Nome(VARCHAR) , Email(VARCHAR) , Credito(INT)
I wanted to know how, or with what command, to decrease or increase the Credito field.
I know you have to use UPDATE but I've already tried several ways and I could not.
You did not give too many details of what you are using, nor did you show what you tried so I will give you a generic answer to increment the value of one to the field in MySQL which I think is the likely DB you are using focus more on your question):
$sql = "UPDATE tabela SET Credito = Credito + 1 WHERE Email = '$email'";
$resultado = mysqli_query($conexao, $sql)
I placed GitHub for future reference .
I'm assuming that the variable is properly sanitized .
Or you can use a parameterized form to execute but the query SQL will be equal to this one.