To pick one industry, click on the row selector into desired community. To choose numerous areas, hold down new Ctrl secret, and click the fresh row selector for every single profession.
If you prefer your order of areas into the a multiple-field primary key to differ from your order of them fields from the dining table, simply click Spiders on the toolbar to demonstrate the fresh Spiders dialog container, and reorder industry labels on the directory named PrimaryKey.
Referential ethics
Referential integrity was a system regarding legislation you to Access spends so you’re able to make certain that relationships anywhere between details during the relevant dining tables try good, and that you do not affect delete or alter associated study. You could put referential ethics when most of the adopting the standards is true:
- This new coordinating career from the no. 1 desk try a primary key or keeps a different sort of directory.
- The new associated fields have the same study variety of. There are two exceptions. A keen AutoNumber career is going to be linked to a variety job that provides an effective FieldSize possessions form off Much time Integer, and you may an enthusiastic AutoNumber profession who has a beneficial FieldSize property function out-of Replication ID will likely be linked to a variety industry who has a beneficial FieldSize property means from Duplication ID.
- Each other dining tables belong to a similar Access databases. Whether your dining tables are linked dining tables, they have to be tables from inside the Availableness format, and you have to unlock this new her promosyon kodu ücretsiz database in which he’s stored to create referential ethics. Referential stability can’t be implemented getting connected dining tables off databases inside most other formats.
- You can’t enter into a regard about overseas trick realm of the newest relevant desk that does not exists however trick of the top desk. However, you can enter into a great Null worthy of regarding foreign trick. Which determine your facts are not related. Like, you can’t has your order that is allotted to a customers who not exists. But not, you’ll have an order that is assigned to no one because of the typing a great Null worth throughout the CustomerID job.
- You simply can’t remove an archive out of a primary table in the event that complimentary facts occur within the a related desk. Particularly, you simply can’t remove an employee record throughout the “Employees” table in the event the you’ll find orders assigned to the newest personnel from the “Orders” desk.
- You can not changes a first secret worthy of regarding priple, you can not change an enthusiastic employee’s ID from the “Employees” dining table when the you’ll find sales assigned to one to worker on “Orders” dining table.
Cascading condition and you will deletes
Getting relationship where referential stability are enforced, you might specify if or not you would like Accessibility automatically cascade up-date otherwise cascade erase associated records. For those who lay these types of choices, remove boost surgery who does always be avoided from the referential integrity rules was permitted. After you delete suggestions otherwise change first trick thinking within the a number 1 desk, Accessibility helps make the called for transform so you can associated dining tables in preserving referential ethics.
For folks who click to choose the Cascade Up-date Relevant Fields see field when you describe a romance, at any time you change the number 1 trick off an archive in the primary table, Microsoft Accessibility instantly standing the primary key to new worth in most relevant facts. Like, for people who change a customer’s ID in the “Customers” dining table, new CustomerID occupation from the “Orders” table is actually immediately upgraded per certainly one of you to definitely user’s sales so that the matchmaking isn’t broken. Access cascades reputation instead of showing any content.
If the number one key in the main table was an enthusiastic AutoNumber career, choosing the Cascade Improve Relevant Areas glance at container has no effect because you cannot alter the worth in the a keen AutoNumber industry.