How to create a relation

We know about relations in VFP and that they are used to tie two tables together using key-fields (usally a primary key and a foreign key). In Servoy this is also the case. However there are a few differences as well.

In VFP we have referential integrity and cascading deletes but the relation only applies to our native Visual FoxPro tables. In Servoy the relation is more of a logical object telling the application how tables are related in stead of forming the actual relation.

With this information Servoy takes care of everything like applying key-values to the specified fields in the database when adding records or filtering the data of a related table to match only the corresponding child-records.

In Servoy relations can also be used to join tables from completely different databases.

Lets take a look at a typical one-to-many data-entry scenario where parent and child records are combined in one form. In this example we will use the customers/orders tables from the example_data database.

In your solution locate the Relations node and right-click it
From the popup-menu select Create relation
Press the Source select button
Expand the example_data database and select the Customers table
Press Ok button

Press the Destination select button
Expand the example_data database and select the Orders table
Press Ok button
Press Ctrl+S to save the relation

That's all! Now we are ready to use the relation in situations where data-entry is done in related tables. To see this relation put to practice go to the Add a portal (vfp: grid) to a form walkthrough. Note that if you did not fill in the relationname yourself that Servoy generated one based on the tables you chose (customers_to_orders).

External resources:

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Official Servoy website

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How to create a relation

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