To choose that career, click the line selector towards the wanted career. To select several sphere, hold-down the Ctrl key, and click the latest line selector for every single community.
If you like the order of the industries from inside the a parallel-field number 1 key to range from the transaction of those sphere on table, mouse click Spiders to the toolbar showing this new Spiders dialog container datingranking.net/tr/jeevansathi-inceleme/, immediately after which reorder industry brands towards the directory named PrimaryKey.
Referential ethics
Referential integrity are a network away from statutes that Supply spends in order to guarantee that dating between information when you look at the relevant dining tables are valid, and you do not happen to erase or change associated analysis. You might place referential ethics when most of the following the standards is actually true:
- The fresh matching career in the no. 1 desk try a primary secret otherwise enjoys a new index.
- The fresh new relevant sphere have a similar studies type of. There are two exclusions. An enthusiastic AutoNumber industry shall be connected with a number profession you to definitely has a great FieldSize assets means regarding A lot of time Integer, and you may an AutoNumber profession who’s got an excellent FieldSize assets function away from Duplication ID will be linked to several career who’s an effective FieldSize property setting out-of Replication ID.
- One another dining tables get into an identical Availability database. In the event your tables is connected tables, they must be dining tables during the Accessibility style, while need to unlock the newest databases in which he’s stored setting referential ethics. Referential integrity cannot be implemented to own linked dining tables out of database within the most other forms.
- You can not go into a respect throughout the overseas key arena of brand new related dining table that will not exist in the primary trick of the number 1 dining table. But not, you might enter a great Null well worth from the foreign trick. Which determine the facts was not related. Including, you can’t has actually an order that’s assigned to a customer that would perhaps not occur. Yet not, you will get an order that’s allotted to no one from the entering a great Null value about CustomerID profession.
- You simply cannot erase accurate documentation off a primary table in the event the complimentary info are present within the an associated desk. Such as for instance, you simply can’t erase an employee listing in the “Employees” table when the you can find instructions assigned to the newest staff member on the “Orders” desk.
- You simply cannot alter a first secret well worth in the priple, you can not alter an enthusiastic employee’s ID regarding “Employees” table when the you’ll find instructions allotted to you to staff throughout the “Orders” desk.
Flowing position and you can deletes
Having matchmaking where referential ethics try enforced, you might identify whether you want Accessibility immediately cascade revision otherwise cascade delete associated facts. For individuals who put these options, erase and update procedures who does constantly be prevented by referential ethics regulations is actually allowed. After you remove ideas or transform top trick beliefs inside a beneficial first table, Accessibility helps to make the requisite changes in order to relevant tables to preserve referential ethics.
For folks who simply click to choose the Cascade Revision Associated Sphere examine package after you describe a relationship, anytime which you alter the top key out-of accurate documentation however dining table, Microsoft Access automatically status the primary key to the brand new really worth throughout relevant suggestions. Such as for example, if you change a consumer’s ID regarding the “Customers” table, the latest CustomerID industry in the “Orders” desk is instantly updated for each one of you to definitely owner’s purchases so that the matchmaking is not damaged. Accessibility cascades condition instead demonstrating people content.
In the event your first input the key dining table is actually an AutoNumber industry, deciding on the Cascade Enhance Related Areas see container does not have any effect since you try not to replace the worth within the an AutoNumber industry.
