Discover the field or sphere that you like so you can establish just like the an important trick

To choose that profession, click the line selector with the wished job. To select numerous industries, hold-down the latest Ctrl secret, and click the brand new row selector for each and every industry.

If you would like the transaction of the sphere inside a multiple-career number one the answer to differ from your order of these fields on desk, simply click Indexes towards the toolbar to exhibit the fresh Indexes dialogue box, and then reorder the field names toward index entitled PrimaryKey.

Referential integrity

Referential ethics was a system from guidelines you to definitely Availability uses in order to make sure dating between suggestions within the associated dining tables are good, and you do not happen to delete otherwise change related analysis. You could potentially put referential ethics when all the after the requirements try true:

  • Brand new complimentary career on the no. 1 table was an initial key or provides an alternate directory.
  • Brand new relevant industries have a similar studies type. There are two exceptions. An enthusiastic AutoNumber community would be pertaining to a number career one possess good FieldSize assets means out of Enough time Integer, and you can an enthusiastic AutoNumber profession who’s got a good FieldSize property form away from Duplication ID might be pertaining to several field having good FieldSize assets setting away from Duplication ID.
  • One another tables fall under a comparable Accessibility database. In the event the dining tables is connected dining tables, they have to be tables into the Access style, and you need unlock new databases where they are stored to put referential integrity. Referential stability can not be implemented to have connected tables regarding databases into the almost every other forms.
  • You simply cannot enter into a regard regarding the overseas trick arena of the latest related desk that will not are present in the main secret of the number 1 desk. Although not, you could enter into good Null worthy of regarding overseas key. This determine the details try not related. Such as, you can’t keeps an order that’s allotted to a customer that would perhaps not can be found. But not, you will get your order which is allotted to no body by typing good Null value regarding the CustomerID industry.
  • You can not delete a record out-of an initial table in the event that complimentary information exist in a related dining table. Such as, you can’t erase an employee record from the “Employees” desk when the you will find requests assigned to the employee from the “Orders” table.
  • You can’t alter a primary key worth from the priple, you simply cannot transform an employee’s ID in the “Employees” table if the discover commands assigned to that staff member about “Orders” table.

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Cascading reputation and you can deletes

Having matchmaking in which referential ethics is enforced, you could potentially specify whether or not you need The means to access immediately cascade revise otherwise cascade erase associated ideas. For individuals who lay these types of possibilities, delete boost operations who usually be avoided by referential integrity statutes is permitted. When you delete facts otherwise alter first key opinions from inside the a beneficial number one dining table, Access helps to make the expected alter to help you associated tables in preserving referential ethics.

For folks who simply click to search for the Cascade Inform Relevant Fields see box after you identify a romance, when you alter the first secret of a record in the primary table, Microsoft Accessibility immediately condition the main the answer to new well worth in all relevant information. Such as for instance, for many who alter a customer’s ID regarding “Customers” table, new CustomerID industry regarding the “Orders” table try instantly upgraded for each among one to customer’s requests so that the matchmaking is not broken. Supply cascades condition as opposed to displaying any content.

When your number one type in the primary desk was a keen AutoNumber industry, deciding on the Cascade Revision Relevant Industries check field does not have any feeling as you cannot replace the value inside a keen AutoNumber field.


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