If defined as NOT NULL, the value corresponds to the start time associated with the most recent transaction (the value of the as ROW BEGIN column).

如果定义为NOT NULL，该值会对应于与最近的事务相关联的开始时间(AS ROW begin列的值)。

youdao

For example, if a before trigger supplies value to a NOT NULL column, then the before trigger is executed first and a value is supplied to the column so that the NOT NULL constraint isn't violated.

例如，如果一个BEFORE触发器给一个NOT null列提供值，那么先执行BEFORE触发器，给列提供值，所以不会违反NOT NULL约束。

youdao

But in DB2, you must provide a value for NOT NULL columns in an INSERT statement when a default hasn't been defined.

但在DB 2中，如果未定义该值，则必须在insert语句中为NOT null列提供值。

youdao