How do I add all of a table in MySQL for example ..
I have the table
tb_comment , so I want to add in each
post(id_mark) the amount of rate that will have the total.
id_user 20 has the rate of 4 in
id_mark 10 and
id_user 21 has the rate of 5 in
id_mark 10 and will give 9 to the total how do I select this in PDO?