Question

How do I write a query to update my rows ‘S’. I would like to update the current Primary key to change the number of it. I am not sure if I need a sub-query.
Would updating score, use the same method to update “S”?
“S” indicates student number, “C” indicates course number.

My tried but failed query is

update grades set s = 114 where s = 100; 

The ‘set s’ is what I want to update into and the ‘where s’ is looking for the row with that set ‘s’ number. Right?

Here is my query, trigger, and select * from grades looks like.

create table grades (
S varchar2(12),
C varchar2(10),
Score number(3,0),
Letter_Grade char(1),
Constraint pk_grades primary key (S),
Constraint CK_grades check (score between 0 and 100)
constraint lg_grades check (letter_grade  in ('A','B','C','D','F'))
);

SET SERVEROUTPUT ON
CREATE OR REPLACE TRIGGER MARK_BU
BEFORE UPDATE OF score ON grades
FOR EACH ROW
DECLARE
BEGIN
:NEW.letter_grade :=
 CASE 
    WHEN :NEW.score >= 80 THEN 'A'
    WHEN :NEW.score >= 70 THEN 'B'
    WHEN :NEW.score >= 60 THEN 'C'
    WHEN :NEW.score >= 50 THEN 'D'
   ELSE 'F'
END ;
DBMS_OUTPUT.PUT_LINE ('Numeric_grade was updated to:    ' || :NEW.score);
DBMS_OUTPUT.PUT_LINE ('Letter_grade was calculated to be:' || :NEW.letter_grade);
END;

S            C               SCORE L
------------ ---------- ---------- -
100          CST8255            49 F
101          CST8255            59 D
102          CST8255            69 C
103          CST8255            79 B
104          CST8255            89 A

Answer 1

update grades set s = 114 where s = 100; 

Is correct it will work.