如果它没有被指定，系统会使用一个全约束名称。

If it is not specified, the system USES the fully qualified constraint name.

youdao

当想要更改约束所附加到的列、更改约束名称或设置约束的附加属性时，可修改唯一约束。

Modify a unique constraint when you want to change the columns that the constraint is attached to, change the constraint name, or set additional properties for the constraint.

youdao

该元素包含约束描述和角色名称(先前在部署描述符中定义过)。

This element contains the description of the constraint and the name of the role (previously defined in the deployment descriptor).

youdao