oracle - 尝试在oracle中编辑特定字段时如何将新值与oracle表单字段中的先前值进行比较

Question

我有一个有日期字段的预言机。该字段可以为空、系统日期、回溯日期或未来日期。如果它有一个过去的日期，字段应该不能修改。如果它为空或未来日期，用户应该能够修改该字段。如果该字段有过去的日期，我该如何限制用户？

Answer 1

If I understand your description correctly, you want the form field to be editable only if the current value (retrieved from the row currently stored in the database, I presume) is NULL or in the future.

To do that, I'd put some logic in the POST-QUERY trigger to disable the item, e.g.

IF :MYBLOCK.MYDATEITEM <= SYSDATE THEN
  SET_ITEM_PROPERTY('MYBLOCK.MYDATEITEM', ENABLED, PROPERTY_FALSE);
END IF;

There are other ways of doing the same thing, e.g. by setting the following properties:

IF :MYBLOCK.MYDATEITEM <= SYSDATE THEN
  SET_ITEM_PROPERTY('MYBLOCK.MYDATEITEM', NAVIGABLE, PROPERTY_FALSE);
  SET_ITEM_PROPERTY('MYBLOCK.MYDATEITEM', INSERT_ALLOWED, PROPERTY_FALSE);
  SET_ITEM_PROPERTY('MYBLOCK.MYDATEITEM', UPDATE_ALLOWED, PROPERTY_FALSE);
END IF;