sql - 更改表添加约束时出错

我想在表名Account，属性名Type中添加约束。
在Type中，我要添加帐户类型，例如：Saving, Credit Card, Home Loan, Personal Loan, Fixed Deposit, Current, iSaver.

这是我的代码：

ALTER TABLE ACCOUNT
ADD CONSTRAINT AccountCK_Type
CHECK (TYPE IN('Saving','Credit Card','Home Loan','Personal Loan','Fixed Deposit','Current','iSaver'));

错误显示：

>Error report -
>
>SQL Error: ORA-02293: cannot validate (SHT461.ACCOUNTCK_TYPE) - check constraint violated
>02293. 00000 - "cannot validate (%s.%s) - check constraint violated"
>
>*Cause:    an alter table operation tried to validate a check constraint to
>           populated table that had nocomplying values.
>
>*Action:   Obvious

请建议我如何添加约束。谢谢。

最佳答案

如注释中所述，如果仅希望约束应用于将来的数据更改，则可以使用NOVALIDATE clause使其忽略其他现有值：

ALTER TABLE ACCOUNT
ADD CONSTRAINT AccountCK_Type
CHECK (TYPE IN('Saving','Credit Card','Home Loan','Personal Loan',
  'Fixed Deposit','Current','iSaver'))
ENABLE NOVALIDATE;

否则，您将必须清理现有数据-在创建约束之前用该列中的任何其他值删除或纠正行。