To choose one to industry, click on the row selector with the wished community. To pick several fields, hold down brand new Ctrl trick, and then click the newest line selector for each industry.
If you need your order of your own fields into the a simultaneous-occupation primary key to differ from the order ones sphere in the table, mouse click Indexes towards toolbar showing the fresh new Spiders dialog box, and reorder industry brands towards index called PrimaryKey.
Referential integrity is actually a system of statutes one to Availableness spends so you’re able to make certain that matchmaking anywhere between info inside related dining tables are legitimate, and you don’t affect remove otherwise transform relevant analysis. You can lay referential stability when most of the following the criteria is actually true:
- The latest complimentary job throughout the first dining table are a primary secret or possess an alternate directory.
- New associated fields have a similar investigation sort of. There’s two conditions. An enthusiastic AutoNumber occupation might be pertaining to several community one to has actually a FieldSize possessions form out-of Much time Integer, and a keen AutoNumber field that a good FieldSize assets form regarding Duplication ID are about a variety industry who’s got an effective FieldSize assets form of Replication ID.
- Each other dining tables fall into the same Availableness database. Whether your dining tables is connected tables, they have to be tables when you look at the Supply style, and also you need to open the brand new database where he or she is kept to put referential stability. Referential integrity cannot be implemented having connected dining tables away from databases into the most other types.
- You can not get into an admiration in the international trick field of the new associated dining table that will not exists in the primary secret of your number one desk. Although not, you might get into an effective Null worthy of in the foreign key. This specifies the details was unrelated. For example, you can not features your order that’s allotted to a buyers that would perhaps not exists. Although not, you could have your order that’s allotted to no one because of the entering good Null worthy of regarding CustomerID field.
- You can’t remove accurate documentation out of a primary dining table when the coordinating facts occur in a related desk. For example, you can’t remove a member of staff number regarding the “Employees” desk when the you will find requests allotted to this new staff member regarding the “Orders” dining table.
- You cannot changes a primary trick really worth regarding priple, you can’t alter an employee’s ID on the “Employees” dining table if the you can find orders assigned to one personnel throughout the “Orders” desk.
Streaming standing and you may deletes
To own dating in which referential integrity is actually enforced, you can indicate whether you want Usage of instantly cascade revise otherwise cascade remove relevant info. For those who set this type of choice, remove boost surgery that would usually be prevented of the referential ethics guidelines is enabled. After you erase info otherwise change number 1 key values when you look at the an effective top desk, Availableness helps to make the called for transform so you’re able to relevant dining tables in preserving referential ethics.
For folks who simply click faceflow to search for the Cascade Up-date Related Fields glance at box when you establish a love, any time which you alter the no. 1 secret out of an archive however dining table, Microsoft Availableness immediately status the primary key to this new value in every associated information. Such as, for those who alter a consumer’s ID in the “Customers” dining table, this new CustomerID community about “Orders” table is actually automatically up-to-date for every one of one customer’s sales and so the dating is not broken. Supply cascades updates rather than demonstrating any message.
When your primary input the main dining table try an enthusiastic AutoNumber career, choosing the Cascade Enhance Related Fields evaluate field doesn’t have effect as you never alter the well worth within the an enthusiastic AutoNumber industry.