Oracle PL/SQL Tutorial/Cursor/refcursor

Reference cursor type

   <source lang="sql">

SQL> SQL> create table t ( x varchar2(5) ); Table created. SQL> SQL> declare

 2      type rc is ref cursor;
 3      l_cursor rc;
 4  begin
 5      for i in 1 .. 5000
 6      loop
 7          open l_cursor for "select x from t where x = " || to_char(i);
 8          close l_cursor;
 9      end loop;
10  end;
11  /

PL/SQL procedure successfully completed. SQL> SQL> declare

 2      type rc is ref cursor;
 3      l_cursor rc;
 4  begin
 5      for i in 1 .. 5000
 6      loop
 7          open l_cursor for "select x from t where x = :x" using i;
 8          close l_cursor;
 9      end loop;
10  end;
11  /

PL/SQL procedure successfully completed. SQL> SQL> drop table t; Table dropped. SQL> SQL></source>

reference cursor variable

   <source lang="sql">

SQL> SQL> SQL> SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,

 2                    ENAME VARCHAR2(10),
 3                    JOB VARCHAR2(9),
 4                    MGR NUMBER(4),
 5                    HIREDATE DATE,
 6                    SAL NUMBER(7, 2),
 7                    COMM NUMBER(7, 2),
 8                    DEPTNO NUMBER(2));

Table created. SQL> SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created. SQL> SQL> SQL> variable a refcursor SQL> variable b refcursor SQL> variable c refcursor SQL> alter session set sql_trace=true; Session altered. SQL> begin

 2      open :a for select empno from emp q1 where ename = "BLAKE";
 3      open :b for select empno from emp q2 where ename = "BLAKE";
 4      open :c for select empno from emp q3 where ename = "SMITH";
 5  end;
 6  /

PL/SQL procedure successfully completed. SQL> print a

    EMPNO

---

     7698

SQL> begin

 2      for i in 1 .. 1000
 3      loop
 4          update emp set sal = sal where ename = "BLAKE";
 5          commit;
 6      end loop;
 7      delete from emp
 8       where ename = "SMITH";
 9      commit;
10  end;
11  /

PL/SQL procedure successfully completed. SQL> print b

    EMPNO

---

     7698

SQL> print c

    EMPNO

---

     7369

SQL> SQL> alter session set sql_trace=false; Session altered. SQL> drop table emp; Table dropped. SQL></source>

return sys_refcursor from a function

   <source lang="sql">

SQL> CREATE TABLE EMP(

 2      EMPNO NUMBER(4) NOT NULL,
 3      ENAME VARCHAR2(10),
 4      JOB VARCHAR2(9),
 5      MGR NUMBER(4),
 6      HIREDATE DATE,
 7      SAL NUMBER(7, 2),
 8      COMM NUMBER(7, 2),
 9      DEPTNO NUMBER(2)
10  );

Table created. SQL> INSERT INTO EMP VALUES(2, "Jack", "Tester", 6,TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES(3, "Wil", "Tester", 6,TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES(4, "Jane", "Designer", 9,TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(5, "Mary", "Tester", 6,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES(7, "Chris", "Designer", 9,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES(8, "Smart", "Helper", 4,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES(9, "Peter", "Manager", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES(10, "Take", "Tester", 6,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES(13, "Fake", "Helper", 4,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> SQL> create or replace function emp_list return sys_refcursor is

 2   rc sys_refcursor;
 3   begin
 4   open rc for select * from emp;
 5   return rc;
 6   end;
 7  /

Function created. SQL> SQL> create or replace procedure list_emps is

 2   e sys_refcursor;
 3   r emp%rowtype;
 4  begin
 5   e := emp_list;
 6   loop
 7       fetch e into r;
 8       exit when e%notfound;
 9       dbms_output.put_line(r.empno||","||r.hiredate);
10   end loop;
11   close e;
12   end;
13  /

Procedure created. SQL> SQL> drop table emp; Table dropped.</source>