Question

说我有一个包含created，uploaded，processed和archived列的表格，所有这些列都接受日期。但是，我想要它，所以字段必须按时间顺序更新，你不能跳过一个步骤，但不必设置尾随步骤，直到它们准备好（即创建）＆lt; = uploaded＆lt; = processed＆lt; = archived）。我这样实现了这个：

create table batch (
  id        number primary key,
  created   date   default sysdate not null,
  uploaded  date,
  processed date,
  archived  date,

  check (uploaded  is null or uploaded  >= created),
  check (processed is null or processed >= uploaded),
  check (archived  is null or archived  >= processed)
);

这有效，但它允许您跳过步骤。例如，如果processed仍为uploaded，我可以为null插入任意值。我认为这是因为null比较总是空洞的。因此，我必须做以下事情：

create table batch (
  id        number primary key,
  created   date   default sysdate not null,
  uploaded  date,
  processed date,
  archived  date,

  check (uploaded  is null or uploaded >= created),
  check (processed is null or (uploaded is not null and processed >= uploaded)),
  check (archived  is null or (processed is not null and archived >= processed))
);

有更简洁的方法吗？

Answer 1

我认为你的设计很健全。我会按时间顺序和NULL检查拆分检查，但这只是样式的问题，而不是逻辑问题。

create table batch (
  id        number primary key,
  created   date   default sysdate not null,
  uploaded  date,
  processed date,
  archived  date,

  CHECK (created <= uploaded),
  CHECK (uploaded <= processed),
  CHECK (processed <= archived),

  CHECK (uploaded IS NOT NULL OR processed IS NULL),
  CHECK (processed IS NOT NULL OR archived IS NULL)
);

Answer 2

最后，我选择了自己的解决方案：

create table batch (
  id        number primary key,
  created   date   default sysdate not null,
  uploaded  date,
  processed date,
  archived  date,

  check (uploaded  is null or uploaded >= created),
  check (processed is null or (uploaded is not null and processed >= uploaded)),
  check (archived  is null or (processed is not null and archived >= processed))
);

当然，正如Jorge所提到的那样，这限制了这个静态模式的工作流程，但这是我愿意接受的权衡！

Answer 3

您可以创建4个表格。每个过程一个。

batches_created
batches_uploaded
batches_processed
batches_archived

create table batches_created (  
  id        number primary key,  
  created   date   default sysdate not null  
);

create table batches_uploaded (  
  id        number primary key,  
  created   date   default sysdate not null,  
  constraint fk_batch_uploaded FOREIGN KEY( id ) REFERENCES batches_created( id )  
);

create table batches_processed (
  id        number primary key,  
  created   date   default sysdate not null,  
  constraint fk_batch_processed FOREIGN KEY( id ) REFERENCES batches_uploaded( id )  
);

create table batches_archived (  
  id        number primary key,  
  created   date   default sysdate not null,  
  constraint fk_batch_archived FOREIGN KEY( id ) REFERENCES batches_processed( id )  
);

因此，如果没有先创建批处理，上传它，然后处理它，就不能存档。

表列的顺序约束

3 个答案: