>>To enforce the relationships, just use the referential integrity builder that comes with Visual FoxPro, or an alternative RI-builder.
>
>>Whether you use primary keys made up of a single field or composite keys, the relationship is from one index to another index. It works exactly the same way.
>
>I was indeed confused, probably because of my ignorance of the VFP database. I thought that creating a relationship from one index to another was already enforcing data integrity. I have to read some more documentation !

To create the RI:

Open the database from the project, or with MODIFY DATABASE.

Make sure you have the required indices.

From the parent table, drag a primary or candidate index, to a regular index in the child table.

You may repeat this for several more relationships.

Before continuing with the next step, you may have to pack ("clean up") the database. One of the last commands in the "Database" menu.

Right-click on the database area (outside of a table), and select "Referential Integrity".

Here, you decide which rules you want to enforce.

Normally, you would put "Restrict / Restrict / Restrict". In some specific cases, you may want to use cascading delete. If the data in the child table is optional (won't always point to a valid parent), you may put "Ignore" for the "Insert" part.

You may also want to see my article, http://www.utmag.com/wconnect/wc.dll?9,7,10,1589

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