求翻译：主键是一张表中唯一区分各行的一组字段。Employee表的主键是Employee ID字段。Works In relationship中的主键包括Office Code及Employee ID字段。给数据库中每一relationship给出一个键，从其所连接的每一个table中抽取其键产生。是什么意思？

The primary key is a group of fields in a table only to distinguish between the lines. employee table primary key is the employee id field. works in the relationship in the primary key, including the Office code and the employee id field. Each relationship is given a key to the database, extract its

The key is a unique distinction in the table rows, a group of fields. Employee table's primary key is Employee ID field. Works In relationship including the primary key and Employee Office Code ID field. In the database for each of the relationship to the one of the keys from the connection of each

The principal linkage is in a table only differentiates each line of group of field.The Employee table principal linkage is Employee the ID field.In Works In relationship principal linkage including Office Code and Employee ID field.Each relationship gives a key for the database in, from in each tab

Primary key is a set of fields that uniquely distinguish between rows in a table. Employee ID field is the primary key of the Employee table. Works In relationship in the primary key includes the Office Code and Employee ID field. Give each a key relationship in a database, from which the extract it