To select one occupation, click the row selector towards the desired industry. To select numerous fields, hold-down new Ctrl key, and click brand new row selector for each and every industry.
If you prefer your order of the fields inside the a multiple-job number one the answer to differ from your order ones sphere on the table, simply click Indexes towards the toolbar to demonstrate the new Indexes dialogue box, right after which reorder industry brands on the directory named PrimaryKey.
Referential ethics
Referential ethics is actually a system out-of laws you to definitely Availability uses to make certain that relationship ranging from suggestions into the associated tables was appropriate, and you don’t occur to delete or alter associated studies. You can place referential integrity whenever most of the adopting the criteria try true:
- The brand new matching profession regarding the no. 1 dining table are an initial trick or possess another type of index.
- The fresh associated areas have a similar studies sort of. There have been two exclusions. An AutoNumber profession is going to be linked to several profession one to features a FieldSize possessions setting off Enough time Integer, and you may an enthusiastic AutoNumber profession who’s good FieldSize property form regarding Duplication ID will be connected with a number field that a great FieldSize property means out of Replication ID.
- One another dining tables belong to a similar Supply databases. In the event your dining tables is linked tables, they have to be tables from inside the Availableness style, while must unlock the brand new databases where they are stored to put referential stability. Referential stability can not be enforced to possess connected dining tables regarding databases in the other formats.
- You can’t enter an esteem on the overseas secret arena of the new associated desk that does not exist in the main key of top dining table. However, you can go into a good Null worth from the international trick. Which determine the ideas are unrelated. Such as for instance, you cannot possess your order that’s allotted to a consumer that would perhaps not are present. Although not, you could have an order that is allotted to no body by the entering an effective Null worthy of on the CustomerID industry.
- You can not delete a record out-of a first table if the complimentary info are present when you look at the an associated desk. Such as for example, you can not remove a member of staff list throughout the «Employees» dining table hornet nasıl çalışır? in the event that you can find requests allotted to the fresh staff member from the «Orders» dining table.
- You simply can’t alter a primary trick value on the priple, you simply can’t transform a keen employee’s ID from the «Employees» desk in the event that discover instructions assigned to that worker throughout the «Orders» dining table.
Cascading condition and you will deletes
For relationships where referential integrity are enforced, you can indicate if you would like The means to access automatically cascade modify otherwise cascade remove related suggestions. If you put this type of alternatives, delete boost businesses who would always be avoided by referential stability regulations is let. When you delete info or transform number one secret philosophy within the an effective top table, Availability helps make the necessary alter to related dining tables in preserving referential stability.
For many who simply click to select the Cascade Posting Related Fields examine field when you describe a romance, any time that you replace the no. 1 trick of an archive however dining table, Microsoft Availableness immediately reputation the key the answer to new value in most related ideas. Including, for people who alter a consumer’s ID throughout the «Customers» table, the newest CustomerID community regarding «Orders» dining table are immediately current each among that user’s commands and so the relationships is not busted. Supply cascades standing versus demonstrating one message.
In case your number 1 input the primary dining table is an enthusiastic AutoNumber occupation, deciding on the Cascade Posting Relevant Areas have a look at container does not have any impression because you cannot change the well worth from inside the an AutoNumber industry.