Oracle PL/SQL -检查输入参数是否为目录

FUNCTION is_directory(p_directory_path IN VARCHAR2) RETURN BOOLEAN IS
  l_directory_exists BOOLEAN;
BEGIN
  SELECT CASE WHEN COUNT(*) > 0 THEN TRUE ELSE FALSE END
  INTO l_directory_exists
  FROM all_directories
  WHERE directory_path = p_directory_path;

  RETURN l_directory_exists;
EXCEPTION
  WHEN NO_DATA_FOUND THEN
    RETURN FALSE;
END;

DECLARE
  l_directory_path VARCHAR2(100) := '/home/user/documents';
  l_is_directory BOOLEAN;
BEGIN
  l_is_directory := is_directory(l_directory_path);

  IF l_is_directory THEN
    DBMS_OUTPUT.PUT_LINE('输入参数是一个目录');
  ELSE
    DBMS_OUTPUT.PUT_LINE('输入参数不是一个目录');
  END IF;
END;