如何从派生自 SYS_REFCURSOR 的 DBMS_SQL 游标中获取值？

Question

我正在尝试从 DBMS_SQL.TO_CURSOR_NUMBER 迭代游标编号，并遇到问题 - 当我尝试将值拉入变量时，我得到 ORA-01007（变量不在选择列表中）。

这是一个复制我的问题的代码块：

DECLARE
  cur SYS_REFCURSOR;
  nm INTEGER;
  colDescs DBMS_SQL.DESC_TAB2;
  numCols INTEGER;
  val VARCHAR2(3);
BEGIN
  OPEN cur FOR
    SELECT 'x' AS foo, 2 AS bar
    FROM dual;
  nm := DBMS_SQL.TO_CURSOR_NUMBER(cur);
  DBMS_SQL.DESCRIBE_COLUMNS2(nm, numCols, colDescs);

  DBMS_OUTPUT.PUT_LINE(numCols);

  DBMS_OUTPUT.PUT_LINE(DBMS_SQL.FETCH_ROWS(nm));

  DBMS_SQL.column_value(nm, 1, val);
  DBMS_OUTPUT.PUT_LINE(val);

  DBMS_SQL.CLOSE_CURSOR(nm);
EXCEPTION
  WHEN OTHERS THEN
    DBMS_SQL.CLOSE_CURSOR(nm);
    DBMS_OUTPUT.PUT_LINE('borked '||SQLCODE);
END;
/

预期输出：

2
1
x

实际输出：

2
1
borked -1007

Answer 1

您还没有完成DEFINE_COLUMN 步骤； before you fetch:

  DBMS_SQL.DEFINE_COLUMN(nm, 1, val, 3);

所以这行得通：

DECLARE
  cur SYS_REFCURSOR;
  nm INTEGER;
  colDescs DBMS_SQL.DESC_TAB2;
  numCols INTEGER;
  val VARCHAR2(3);
BEGIN
  OPEN cur FOR
    SELECT 'x' AS foo, 2 AS bar
    FROM dual;
  nm := DBMS_SQL.TO_CURSOR_NUMBER(cur);
  DBMS_SQL.DESCRIBE_COLUMNS2(nm, numCols, colDescs);

  DBMS_OUTPUT.PUT_LINE(numCols);

  DBMS_SQL.DEFINE_COLUMN(nm, 1, val, 3);

  DBMS_OUTPUT.PUT_LINE(DBMS_SQL.FETCH_ROWS(nm));

  DBMS_SQL.column_value(nm, 1, val);
  DBMS_OUTPUT.PUT_LINE(val);

  DBMS_SQL.CLOSE_CURSOR(nm);
EXCEPTION
  WHEN OTHERS THEN
    DBMS_SQL.CLOSE_CURSOR(nm);
    DBMS_OUTPUT.PUT_LINE('borked '||SQLERRM);
    DBMS_OUTPUT.PUT_LINE(DBMS_UTILITY.FORMAT_ERROR_BACKTRACE);
END;
/

anonymous block completed
2
1
x