open_cursors 與 ORA-01000

open_cursors 是可以打開的遊標數，如果只打開不關閉，很容易就到上限了

下面我們來做下實驗：

先把值改小一點

SQL> alter system set open_cursors=5;

System altered.

建一proc

CREATE OR REPLACE PROCEDURE p_cur_test(OUT cur SYS_REFCURSOR) AS
BEGIN
  OPEN cur FOR
    SELECT * FROM emp;
END;

多次打開

SQL> DECLARE
  2    TYPE t_cur IS REF CURSOR;
  3    cur1 t_cur;
  4    cur2 t_cur;
  5    cur3 t_cur;
  6  BEGIN
  7    p_cur_test(cur1);
  8    p_cur_test(cur2);
  9    p_cur_test(cur3);
 10  END;
 11  /
PL/SQL procedure successfully completed

這時還沒超限，我們再增加次數

SQL> DECLARE
  2    TYPE t_cur IS REF CURSOR;
  3    cur1 t_cur;
  4    cur2 t_cur;
  5    cur3 t_cur;
  6    cur4 t_cur;
  7    cur5 t_cur;
  8    cur6 t_cur;
  9  BEGIN
 10    p_cur_test(cur1);
 11    p_cur_test(cur2);
 12    p_cur_test(cur3);
 13    p_cur_test(cur4);
 14    p_cur_test(cur5);
 15    p_cur_test(cur6);
 16  END;
 17  /
DECLARE
  TYPE t_cur IS REF CURSOR;
  cur1 t_cur;
  cur2 t_cur;
  cur3 t_cur;
  cur4 t_cur;
  cur5 t_cur;
  cur6 t_cur;
BEGIN
  p_cur_test(cur1);
  p_cur_test(cur2);
  p_cur_test(cur3);
  p_cur_test(cur4);
  p_cur_test(cur5);
  p_cur_test(cur6);
END;
ORA-01000: maximum open cursors exceeded
ORA-06512: at "TEST.P_CUR_TEST", line 3
ORA-06512: at line 13

現在報錯了

再試下每次打開後關閉

SQL> DECLARE
  2    TYPE t_cur IS REF CURSOR;
  3    cur1 t_cur;
  4    cur2 t_cur;
  5    cur3 t_cur;
  6    cur4 t_cur;
  7    cur5 t_cur;
  8    cur6 t_cur;
  9  BEGIN
 10    p_cur_test(cur1);
 11    CLOSE cur1;
 12    p_cur_test(cur2);
 13    CLOSE cur2;
 14    p_cur_test(cur3);
 15    CLOSE cur3;
 16    p_cur_test(cur4);
 17    CLOSE cur4;
 18    p_cur_test(cur5);
 19    CLOSE cur5;
 20    p_cur_test(cur6);
 21    CLOSE cur6;
 22  END;
 23  /
PL/SQL procedure successfully completed

SQL> 

正常結束

恢復參數

SQL> alter system set open_cursors=150;

System altered.