feat: update structure

cs2102/labs/tutorials/tut06-ans.sql

@@ -0,0 +1,79 @@
+CREATE OR REPLACE FUNCTION max_min(IN stu_id INT, OUT max_cid INT, OUT min_cid INT)
+    RETURNS RECORD AS
+$$
+DECLARE
+    max_score INT;
+    min_score INT;
+BEGIN
+    SELECT e.score, e.cid
+    INTO max_score, max_cid
+    FROM exams e
+    WHERE stu_id = e.sid
+      AND e.score = (SELECT MAX(score)
+                     FROM exams
+                     where stu_id = sid);
+    SELECT e.score, e.cid
+    INTO min_score, min_cid
+    FROM exams e
+    WHERE stu_id = e.sid
+      AND e.score = (SELECT MIN(score)
+                     FROM exams
+                     where stu_id = sid);
+
+    IF max_score = min_score THEN
+        min_cid = NULL;
+    END IF;
+END;
+$$ LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION revised_avg(IN stu_id INT, OUT r_avg FLOAT)
+    RETURNS FLOAT AS
+$$
+DECLARE
+    max_score   INT;
+    min_score   INT;
+    sum_score   FLOAT;
+    count_score INT;
+BEGIN
+    SELECT MAX(score), MIN(score), SUM(score), COUNT(score)
+    INTO max_score, min_score, sum_score, count_score
+    FROM exams
+    WHERE sid = stu_id;
+
+    if count_score < 3 THEN
+        r_avg := NULL;
+    ELSE
+        r_avg := (sum_score - max_score - min_score) / (count_score - 2);
+    end if;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION list_r_avg()
+    RETURNS TABLE
+            (
+                stu_id INT,
+                ravg   FLOAT
+            )
+AS
+$$
+DECLARE
+    curs CURSOR FOR (SELECT sid, score
+                     FROM Exams
+                     ORDER BY sid);
+    r RECORD;
+/* add other variables here */
+BEGIN
+    /* write your code here */
+    stu_id := -1;
+    OPEN curs;
+    LOOP
+        FETCH curs INTO r;
+        if r.sid <> "".stu_idOR NOT FOUND THEN
+
+        end if;
+
+    end loop;
+    CLOSE curs;
+END;
+$$ LANGUAGE plpgsql;