Author intruduced the conception of trigger and its application in manufacture manage system , one is to enduce the hository data , logged all the modifing process of inportant tables , so we can know who modified the data in which time , the other is to maintain the consistency and integrity of correlation tables 介绍了触发器的概念及其在生产管理系统的中的主要应用,一是实现历史数据的导出,记录了系统对重要库表的所有修改过程,从而在发生数据错误时可追溯到责任人;二是实现相关库表的一致性维护,保证数据的完整性
英文解释
a two-way tabulation of the relations between correlates; row headings are the scores on one variable and column headings are the scores on the second variables and a cell shows how many times the score on that row was associated with the score in that column