Nested cursor : Introduction « Cursor « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Cursor
3. Introduction

SQL>
SQL> CREATE TABLE emp (
  2    id         NUMBER PRIMARY KEY,
  3    fname VARCHAR2(50),
  4    lname  VARCHAR2(50)
  5  );

Table created.

SQL>
SQL> INSERT INTO emp (id, fname, lname)VALUES (1, 'A', 'B');

1 row created.

SQL> INSERT INTO emp (id, fname, lname)VALUES (2, 'C', 'D');

1 row created.

SQL> INSERT INTO emp (id, fname, lname)VALUES (3, 'Enn', 'F');

1 row created.

SQL> INSERT INTO emp (id, fname, lname)VALUES (4, 'G', 'H');

1 row created.

SQL> INSERT INTO emp (id, fname, lname)VALUES (5, 'G', 'Z');

1 row created.

SQL>
SQL>
SQL> CREATE TABLE books (
  2    isbn      CHAR(10) PRIMARY KEY,
  3    category  VARCHAR2(20),
  4    title     VARCHAR2(100),
  5    num_pages NUMBER,
  6    price     NUMBER,
  7    copyright NUMBER(4),
  8    emp1   NUMBER,
  9    emp2   NUMBER,
 10    emp3   NUMBER
 11  );

Table created.

SQL>
SQL> INSERT INTO books (isbn, category, title, num_pages, price, copyright, emp1, emp2, emp3)
  2             VALUES ('1', 'Database', 'Oracle', 563, 39.99, 2009, 1, 2, 3);

1 row created.

SQL> INSERT INTO books (isbn, category, title, num_pages, price, copyright, emp1, emp2)
  2             VALUES ('2', 'Database', 'MySQL', 765, 44.99, 2009, 4, 5);

1 row created.

SQL> INSERT INTO books (isbn, category, title, num_pages, price, copyright, emp1, emp2, emp3)
  2             VALUES ('3', 'Database', 'SQL Server', 404, 39.99, 2001, 6, 7, 8);

1 row created.

SQL>
SQL> SET SERVEROUTPUT ON ESCAPE OFF
SQL>
SQL> DECLARE
  2
  3     cv_emp SYS_REFCURSOR;
  4     v_title BOOKS.TITLE%TYPE;
  5     v_emp emp%ROWTYPE;
  6     v_counter PLS_INTEGER := 0;
  7
  8     CURSOR book_cur IS SELECT b.title,CURSOR (SELECT * FROM emp a WHERE a.id = b.emp1 OR a.id = b.emp2 OR a.id = b.emp3)
  9        FROM books b
 10        WHERE isbn = '1';
 11
 12  BEGIN
 13
 14     DBMS_OUTPUT.ENABLE(1000000);
 15
 16     OPEN book_cur;
 17
 18     LOOP
 19        FETCH book_cur INTO v_title, cv_emp;
 20        EXIT WHEN book_cur%NOTFOUND;
 21
 22        v_counter := 0;
 23
 24        DBMS_OUTPUT.PUT_LINE('Title from the main cursor: '||v_title);
 25
 26        LOOP
 27           FETCH cv_emp INTO v_emp;
 28           EXIT WHEN cv_emp%NOTFOUND;
 29
 30           v_counter := v_counter + 1;
 31
 32           DBMS_OUTPUT.PUT_LINE('emp'||v_counter||': '||v_emp.fname||' '||v_emp.lname);
 33        END LOOP;
 34     END LOOP;
 35
 36     CLOSE book_cur;
 37
 38  END;
 39  /
Title from the main cursor: Oracle
emp1: Enn F
emp2: C D
emp3: A B

PL/SQL procedure successfully completed.

SQL> drop table emp;

Table dropped.

SQL> drop table books;

Table dropped.