Constraints Supports, primary, foreign, unique, not null constraint.

约束 支持主键、外键、惟一和非空约束。

youdao

So in the example above, the NOT NULL constraint would get violated, and the INSERT statement would error out.

因此，在上面的示例中，会违反 NOT NULL 约束，INSERT 语句会出错。

youdao

In Oracle 10g, if there is a BEFORE INSERT TRIGGER and a NOT NULL constraint on a table, then the BEFORE TRIGGER is executed first, and then the constraint check is performed.

在Oracle 10 g中，如果表上同时存在BEFORE INSERT触发器和NOT NULL约束，那么先执行BEFORE触发器，然后执行约束检查。

youdao