A trigger that includes either select statements that return results to the user or statements that perform variable assignment requires special handling ; these returned results would have to be written into every application in which modifications to the trigger table are allowed 包含向用户返回结果的select语句或进行变量赋值的语句的触发器需要特殊处理；这些返回的结果必须写入允许修改触发器表的每个应用程序中。
In sql server 2005 integration services ssis , expressions can be used to define conditions for case statements , create and update values in data columns , assign values to variables , update or populate properties at run time , define constraints in precedence constraints , and provide the expressions used by the for loop container 在sql server 2005 integration services ( ssis )中，表达式可以用于定义case语句的条件，创建和更新数据列中的值，为变量赋值，在运行时更新或填充属性，定义优先约束中的约束，以及提供for循环容器所使用的表达式。
