A cursor with a FOR UPDATE clause.
SQL>
SQL> CREATE TABLE lecturer (
2 id NUMBER(5) PRIMARY KEY,
3 first_name VARCHAR2(20),
4 last_name VARCHAR2(20),
5 major VARCHAR2(30),
6 current_credits NUMBER(3)
7 );
Table created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10001, 'Scott', 'Lawson','Computer Science', 11);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major, current_credits)
2 VALUES (10002, 'Mar', 'Wells','History', 4);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10003, 'Jone', 'Bliss','Computer Science', 8);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10004, 'Man', 'Kyte','Economics', 8);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10005, 'Pat', 'Poll','History', 4);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10006, 'Tim', 'Viper','History', 4);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10007, 'Barbara', 'Blues','Economics', 7);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10008, 'David', 'Large','Music', 4);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10009, 'Chris', 'Elegant','Nutrition', 8);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10010, 'Rose', 'Bond','Music', 7);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10011, 'Rita', 'Johnson','Nutrition', 8);
1 row created.
SQL>
SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits)
2 VALUES (10012, 'Sharon', 'Clear','Computer Science', 3);
1 row created.
SQL>
SQL>
SQL> CREATE TABLE session (
2 department CHAR(3),
3 course NUMBER(3),
4 description VARCHAR2(2000),
5 max_lecturer NUMBER(3),
6 current_lecturer NUMBER(3),
7 num_credits NUMBER(1),
8 room_id NUMBER(5)
9 );
Table created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('HIS', 101, 'History 101', 30, 11, 4, 20000);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('HIS', 301, 'History 301', 30, 0, 4, 20004);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('CS', 101, 'Computer Science 101', 50, 0, 4, 20001);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('ECN', 203, 'Economics 203', 15, 0, 3, 20002);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('CS', 102, 'Computer Science 102', 35, 3, 4, 20003);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('MUS', 410, 'Music 410', 5, 4, 3, 20005);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('ECN', 101, 'Economics 101', 50, 0, 4, 20007);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('NUT', 307, 'Nutrition 307', 20, 2, 4, 20008);
1 row created.
SQL>
SQL> INSERT INTO session(department, course, description, max_lecturer, current_lecturer, num_credits, room_id)
2 VALUES ('MUS', 100, 'Music 100', 100, 0, 3, NULL);
1 row created.
SQL>
SQL> CREATE TABLE myStudent (
2 student_id NUMBER(5) NOT NULL,
3 department CHAR(3) NOT NULL,
4 course NUMBER(3) NOT NULL,
5 grade CHAR(1)
6 );
Table created.
SQL>
SQL>
SQL>
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10000, 'CS', 102, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10002, 'CS', 102, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10003, 'CS', 102, 'C');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10000, 'HIS', 101, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10001, 'HIS', 101, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10002, 'HIS', 101, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10003, 'HIS', 101, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10004, 'HIS', 101, 'C');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10005, 'HIS', 101, 'C');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10006, 'HIS', 101, 'E');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10007, 'HIS', 101, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10008, 'HIS', 101, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10009, 'HIS', 101, 'D');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10010, 'HIS', 101, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10008, 'NUT', 307, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10010, 'NUT', 307, 'A');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10009, 'MUS', 410, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10006, 'MUS', 410, 'E');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10011, 'MUS', 410, 'B');
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
2 VALUES (10000, 'MUS', 410, 'B');
1 row created.
SQL>
SQL> DECLARE
2 v_NumCredits session.num_credits%TYPE;
3
4 CURSOR cursorValue IS
5 SELECT *
6 FROM lecturer
7 WHERE id IN (SELECT student_id
8 FROM myStudent
9 WHERE department= 'HIS'
10 AND course = 101)
11 FOR UPDATE OF current_credits;
12
13 BEGIN
14 FOR myLecturerInfo IN cursorValue LOOP
15 SELECT num_credits
16 INTO v_NumCredits
17 FROM session
18 WHERE department = 'HIS'
19 AND course = 101;
20
21 UPDATE lecturer
22 SET current_credits = current_credits + v_NumCredits
23 WHERE CURRENT OF cursorValue;
24 END LOOP;
25 COMMIT;
26 END;
27 /
PL/SQL procedure successfully completed.
SQL>
SQL> drop table session;
Table dropped.
SQL>
SQL> drop table myStudent;
Table dropped.
SQL>
SQL> drop table lecturer;
Table dropped.
SQL>
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