mysql - proper way of inserting data with id as auto-increment in mysqli

Question

can someone please verify the proper way of inserting data using MYSQLI?

i need to insert comment data into the table with ID set as auto-increment. do i just leave the values for id as blank ?

$db = dbConnect();
$query = "INSERT INTO comments values ('', '$comment')";
$db->query($query);

Answer 1

A proper way would be either omit value, or assign NULL to it.
While empty string which is used in your example, is not a valid value and in strict mode it will issue a warning.

INSERT INTO comments VALUES (NULL, 'comment')
INSERT INTO comments (comment) VALUES ('comment')

are all valid.