The rule integrity constraint is an importance constitute part of management in deductive database. 完整性维护是演绎数据库管理中的重要组成部分。
Now imagine you're performing a complicated operation that involves inserting or updating multiple rows in multiple databases, and one of the operations violates an integrity constraint and fails. 现在,假设您正在执行一个复杂的操作,该操作涉及在多个数据库中插入或更新多个行,其中一个操作违反了完整性约束(IC)并失败了。
If Cust-A has an integrity constraint instructing that it must have a sales person, then Cust-A must first be updated to the new Sales-B before Sales-A is deleted. 如果Cust-A有一个完整性约束(IC)来指明它必须拥有一个销售人员,则Cust-A必须先更新到新的Sales-B,然后才能删除Sales-A。
If an update statement violates an integrity constraint, the update does not take place and an error message appears. 如果update语句违反了完整性约束(IC),则不会进行更新并将显示一条错误消息。
With the research of data structure mapping ( table structure mapping and table relation mapping ) and data integrity constraint mapping ( entity integrity mapping and reference integrity mapping ), the mapping rules between XML documents and relational model are detailed discussed. 通过数据结构映射(表结构映射和表联系映射)和数据完整性映射(实体完整性映射和参照完整性映射)的研究,详细地讨论了XML与关系模型之间的映射规则。