To select you to definitely field, click the line selector into the wished career. To pick several areas, hold down the new Ctrl secret, and then click this new line selector for each job.
If you’d like your order of your areas inside a parallel-job first key to range from your order of those fields from the desk, simply click Spiders toward toolbar showing the fresh new Spiders dialog package, right after which reorder industry labels into the list entitled PrimaryKey.
Referential integrity
Referential ethics was a system of laws and regulations one to Availableness uses to make certain matchmaking anywhere between details within the relevant dining tables are appropriate, and that you do not happen to remove otherwise transform related research. You could lay referential ethics whenever all the following standards was true:
- The fresh coordinating profession regarding first table is a first secret otherwise enjoys an alternate directory.
- The fresh related fields have the same studies method of. There’s two exceptions. A keen AutoNumber job will be linked to a number career one keeps a beneficial FieldSize possessions setting of Enough time Integer, and an enthusiastic AutoNumber industry who has a FieldSize property form out-of Duplication ID will likely be related to a number profession having a good FieldSize possessions function away from Duplication ID.
- One another dining tables fall into the same Availability database. If your dining tables try linked dining tables, they must be tables inside the Accessibility structure, therefore must unlock the brand new database where he’s held to put referential ethics. Referential stability can’t be implemented to own linked dining tables of databases when you look at the almost every other types.
- You simply cannot enter into an admiration regarding the overseas key arena of brand new related dining table that will not are present in the main secret of one’s number one table. not, https://datingranking.net/cs/compatible-partners-recenze/ you can enter a Null well worth in the overseas key. Which determine that the suggestions is actually unrelated. Including, you simply cannot keeps your order which is assigned to a customers who not occur. However, you can get your order that is allotted to no-one by the entering a Null really worth about CustomerID career.
- You can’t delete an archive away from a first desk if the coordinating facts exist into the a related desk. Particularly, you can’t remove an employee record regarding the “Employees” desk when the you’ll find instructions allotted to the brand new worker regarding the “Orders” table.
- You simply cannot change an initial trick worth about priple, you can not transform a keen employee’s ID regarding “Employees” table in the event the you can find requests assigned to one staff member in the “Orders” dining table.
Cascading position and you can deletes
To own relationships in which referential stability is implemented, you can indicate whether or not need Accessibility immediately cascade up-date or cascade erase relevant ideas. For many who lay these types of alternatives, remove boost operations that would constantly be avoided by the referential integrity laws is actually let. After you erase facts otherwise changes primary trick opinions inside a beneficial first table, Access helps make the required changes so you can related tables to preserve referential ethics.
For many who mouse click to select the Cascade Change Relevant Areas view container when you establish a romance, at any time you replace the no. 1 trick regarding accurate documentation in the main dining table, Microsoft Access instantly standing the primary the answer to this new value in every associated records. Such as, for many who change a customer’s ID regarding “Customers” dining table, this new CustomerID job on the “Orders” dining table try instantly upgraded per one of one customer’s requests so the matchmaking isn’t broken. Access cascades condition in place of displaying people message.
In case your first key in the key dining table try an enthusiastic AutoNumber career, choosing the Cascade Improve Associated Industries view package does not have any impression because you cannot alter the worth inside the an AutoNumber industry.