sql 来自grad class.sql的成绩

Posted 2021-05-13

alter table student
add grade number(1) generated always as 
     (abs(
        grad_class - 
        (to_number(EXTRACT(YEAR FROM SYSDATE),'9999') +
        case
            when to_number(extract(month from sysdate) , '99') between 7 and 12 then 1
            else 0
        end)
        - 12)
        );