检查类型的约束 [英] Check constraint on a type

问题描述

我有这样的东西:

CREATE TYPE oAuthors AS OBJECT (
    ... ,
    contract CHAR(1),

    CONSTRUCTOR FUNCTION oAuthors (...
);

问题是我想添加一个约束，以便合同中只能包含0或1.
我试图在添加列之后声明添加

The thing is that I wanted to add a constraint to allow only 0 or 1 in contract.
I tried to do so right after the declaration of the column by adding

CONSTRAINT contract_bit CHECK (contract IN ('0','1')),

我也尝试过使用ALTER语句来执行此操作，但是问题是这不是一个表，因此它无法识别它，并且使用ALTER TYPE也不起作用(尽管我只是在尝试，但我没有这样做)不知道该怎么做).

I also tried to do it in an ALTER sentence, but the problem is that this is not a table so it won't recognize it, and using ALTER TYPE doesn't work (although I was just trying, I don't know how to do it).

所以基本上我不知道是否可以通过使用约束来实现，我应该创建触发器还是其他东西?

So basically I have no idea if this is possible by using a constraint, should I create a trigger or something?

推荐答案

您不能定义对象类型的约束: http://docs.oracle.com/cd/B28359_01/server .111/b28286/clauses002.htm

You can't define constraint on object type: http://docs.oracle.com/cd/B28359_01/server.111/b28286/clauses002.htm

您可以通过两种方式在语法上定义约束:

You can define constraints syntactically in two ways:

• 作为单个列或属性的定义的一部分.这称为内联规范.
• 作为表定义的一部分.这称为离线规范

约束子句可以出现在以下语句中:

Constraint clauses can appear in the following statements:

• 创建表(请参阅创建表)
• ALTER TABLE(请参阅ALTER TABLE)
• 创建视图(请参阅创建视图)
• ALTER VIEW(请参阅ALTER VIEW)

以下是您对对象实施约束的方式: http://docs.oracle.com/cd/B28359_01 /appdev.111/b28371/adobjdes.htm#i452285

Here is how you enforce constraints on objects: http://docs.oracle.com/cd/B28359_01/appdev.111/b28371/adobjdes.htm#i452285

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