Get the career or industries that you want to help you establish as the an important trick

0
17

Get the career or industries that you want to help you establish as the an important trick

To pick you to definitely occupation, click the row selector to your desired career. To pick multiple areas, hold down new Ctrl key, and click new line selector for every single career.

If you’d like the transaction of your own sphere inside a multiple-job primary key to differ from the transaction of these areas throughout the dining table, click Spiders on toolbar to exhibit new Spiders dialogue container, right after which reorder the field brands to the directory titled PrimaryKey.

Referential ethics

Referential ethics try a system of rules that Accessibility uses so you can make sure that relationship ranging from records for the associated dining tables was appropriate, and you do not occur to remove otherwise change relevant studies. You can place referential integrity whenever most of the after the requirements was true:

  • The newest matching field in the first table was a first trick or have a different directory.
  • New associated sphere have a similar analysis particular. There are 2 conditions. An AutoNumber profession can be pertaining to a variety career that enjoys a great FieldSize possessions mode away from Much time Integer, and you will a keen AutoNumber community having an excellent FieldSize possessions mode out of Duplication ID are going to be connected with a variety profession having a good FieldSize assets mode from Duplication ID.
  • Each other tables belong to a similar Availability database. Should your tables is connected dining tables, they have to be tables in Availableness structure, and also you have to unlock the newest database where he’s held setting referential ethics. Referential ethics cannot be implemented having linked tables of databases inside almost every other forms.
  • You cannot go into a regard about foreign key realm of the latest related table that does not can be found in the main trick of number one table. Although not, you might go into an effective Null well worth in the international secret. So it specifies that the details was not related. For example, you simply cannot enjoys an order that’s allotted to a consumer that would not exists. But not, you’ll have your order which is assigned to not one person by the entering a great Null really worth regarding the CustomerID occupation.
  • You simply can’t delete an archive regarding a primary desk if complimentary details can be found inside the a connected dining table. Including, you simply can’t erase a member of staff listing throughout the “Employees” desk in the event that there are requests assigned to the latest personnel on the “Orders” dining table.
  • You can’t transform a first secret worth about priple, you can’t alter an employee’s ID from the “Employees” dining table if there are sales assigned to that employee on the “Orders” dining table.

Flowing status and you may deletes

Having dating in which referential integrity try implemented, you could potentially specify whether you would like Usage of immediately cascade up-date otherwise cascade delete relevant facts. For folks who lay these solutions, erase and update operations who would usually be prevented by referential integrity regulations are enabled. Once you remove records or transform number one secret philosophy into the good number one dining table, Access makes the called for transform in order to related dining tables to preserve referential ethics.

For people who click to choose the Cascade Improve Associated Industries glance at field after you define a relationship, at any time you change the top trick out of a record in the primary desk, Microsoft Accessibility instantly updates the key key to this new worth throughout relevant records. Eg, for folks who transform a customer’s ID on the “Customers” dining table, this new CustomerID occupation on the “Orders” table try instantly current per one of you to definitely customer’s orders therefore, the relationships is not broken. Availability cascades reputation instead https://datingranking.net/cs/321chat-recenze displaying one content.

Should your no. 1 input the main table is a keen AutoNumber field, deciding on the Cascade Revise Related Fields take a look at field has no impression since you try not to replace the really worth inside a keen AutoNumber field.

BÌNH LUẬN

Please enter your comment!
Please enter your name here

Website này sử dụng Akismet để hạn chế spam. Tìm hiểu bình luận của bạn được duyệt như thế nào.