Discover the community or industries you want to establish since an important trick

Discover the community or industries you want to establish since an important trick

To select you to definitely profession, click on the line selector into desired community. To pick multiple fields, hold down new Ctrl key, and click the row selector each industry.

If you would like the order of your own fields into the a simultaneous-industry primary the answer to differ from your order of them areas from the dining table, click Spiders to the toolbar to demonstrate the fresh new Indexes dialog container, and then reorder industry names to the list titled PrimaryKey.

Referential stability

Referential ethics was a network regarding guidelines one to Availability spends to guarantee that relationship anywhere between details during the relevant dining tables are valid, and you don’t affect remove or alter associated data. You might place referential stability whenever all the following the requirements is actually true:

  • Brand new coordinating field on primary table was an initial trick or provides an alternate directory.
  • Brand new associated industries have the same data types of. There are two exclusions. An AutoNumber career will be regarding a variety field one to possess an effective FieldSize possessions mode regarding Much time Integer, and you will a keen AutoNumber community who has a FieldSize property function from Duplication ID connexion is going to be associated with lots profession that an excellent FieldSize property mode out of Replication ID.
  • Each other tables fall into an equivalent Availableness database. In the event the dining tables try connected dining tables, they have to be tables in the Availableness structure, and you need open the fresh database in which he or she is held to create referential ethics. Referential stability cannot be implemented to have linked dining tables regarding databases for the almost every other platforms.
  • You can’t enter into a value about overseas trick arena of the fresh relevant table that doesn’t can be found in the primary key of primary desk. Yet not, you can enter an excellent Null well worth about overseas trick. Which specifies that information are unrelated. Like, you simply can’t has your order that’s allotted to a customer who would not can be found. Yet not, you will get your order which is assigned to no-one of the typing a great Null worth in the CustomerID community.
  • You can not delete an archive off a primary table in the event the coordinating suggestions can be found within the a related table. Instance, you can’t erase a member of staff record in the “Employees” table in the event the you will find commands assigned to the fresh staff member regarding the “Orders” table.
  • You simply can’t alter a primary secret value from the priple, you can’t change a keen employee’s ID regarding “Employees” dining table when the discover instructions assigned to you to staff throughout the “Orders” dining table.

Cascading status and you will deletes

To possess relationship in which referential ethics are enforced, you could indicate whether or not you want Entry to automatically cascade improve otherwise cascade erase associated facts. For folks who put these choices, delete and update procedures who does usually be prevented by referential ethics rules is let. After you delete records or transform first secret beliefs from inside the an effective first dining table, Availableness helps to make the requisite transform in order to relevant tables in preserving referential stability.

For people who click to find the Cascade Upgrade Related Areas consider container when you identify a love, any time which you replace the primary trick out-of accurate documentation in the main desk, Microsoft Access instantly condition an important key to brand new value in every related suggestions. Such as for example, for individuals who alter a consumer’s ID from the “Customers” dining table, the latest CustomerID community regarding “Orders” desk is actually immediately up-to-date for each certainly one customer’s commands therefore the matchmaking is not broken. Availability cascades position instead of exhibiting people message.

Whether your number one key in the key table try an AutoNumber community, deciding on the Cascade Improve Relevant Areas view package has no effect because you dont replace the value within the an enthusiastic AutoNumber community.

Elizabeth John

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