To choose one to industry, click the line selector into the desired career. To choose multiple industries, hold-down the fresh new Ctrl trick, and then click the line selector for each and every field.
If you like the transaction of one’s industries inside the a parallel-field primary key to range from your order of these fields from the dining table, click Indexes toward toolbar to demonstrate the latest Spiders dialog container, then reorder industry brands to your index entitled PrimaryKey.
Referential stability
Referential integrity was a network of laws and regulations one to Availability uses to help you guarantee that matchmaking ranging from info in the related dining tables was appropriate, and you do not affect delete or changes related studies. You could potentially lay referential ethics whenever all of the pursuing the conditions are true:
- The fresh new coordinating profession on number one table is an initial key or possess an alternate directory.
- The newest related industries have a similar analysis type. There are two exclusions. An AutoNumber field shall be regarding several job you to possess an effective FieldSize property mode out-of Enough time Integer, and you may an enthusiastic AutoNumber field that has good FieldSize property setting away from Replication ID will be associated with several job that has a beneficial FieldSize assets means of Duplication ID.
- Both dining tables belong to an equivalent Accessibility database. In the event your tables is connected dining tables, they must be dining tables from inside the Accessibility style, therefore have to open the new databases where he could be kept setting referential integrity. Referential ethics can not be implemented to have connected dining tables out-of databases in the other formats.
- You simply can’t get into an admiration on the foreign secret arena of the brand new associated desk that doesn’t can be found in the primary key of number 1 desk. Yet not, you can enter into a great Null worth from the international key. So it specifies your records are not related. Such as for example, you cannot enjoys an order that’s allotted to a buyers who maybe not occur. But not, you could have your order that is assigned to no one of the entering an excellent Null value in the CustomerID industry.
- You simply cannot remove an archive regarding an initial table if coordinating records are present into the a related desk. For example, you cannot delete a member of staff record regarding “Employees” dining table when the you’ll find sales allotted to new personnel throughout the “Orders” desk.
- You cannot change an initial key well worth from the priple, you can’t transform an employee’s ID in the “Employees” table in the event that discover purchases assigned to one staff throughout the “Orders” table.
Cascading status and deletes
To have relationship in which referential integrity is enforced, you might identify whether or not you prefer Use of automatically cascade upgrade otherwise cascade remove associated information. If you set these possibilities, erase boost procedures who would always be prevented from the referential stability statutes are enabled. After you erase information or alter number 1 key beliefs from inside the a good number one desk, Availableness helps make the needed alter in order to related dining tables in preserving referential ethics.
For people who mouse click to determine the Cascade Revision Related Fields look at container after you determine a romance, anytime you change the no. 1 secret regarding accurate documentation however table, Microsoft Supply instantly position the key key to the new really worth throughout associated records. For example, if you change a customer’s ID regarding “Customers” table, this new CustomerID occupation regarding the “Orders” table is immediately current each certainly one to user’s purchases so that the matchmaking is not broken. Supply cascades reputation instead of displaying one content.
Should your no. 1 input the main dining table is actually an AutoNumber profession, deciding on the Cascade Enhance Associated Industries glance at container doesn’t have effect because you do not change the really worth in an AutoNumber job.