仅当when子句的计算结果为真时，触发器语句的操作部分才会执行。

Only if the WHEN clause evaluates to true will the action part of trigger statement be executed.

youdao

如果没有条件为真，则将执行“ else ”操作，如果有一个条件为真，则继续执行整个“ if, elif, else ”语句之后的行。

If none of the conditions are true, it will execute the "else" action, if one is present, and then continue executing lines following the entire "if, elif, else" statement.

youdao

如果结果为真，那么将在触发器语句中根据EMPLOYEE模式验证INFO文档。

If it is true, then the INFO document gets validated against the EMPLOYEE schema in the trigger statement.

youdao