Do foreign keys always have to be specified

Hi Mick,

Foreign keys don’t have to be specified for most purpose they do, although they are not assigned or written as being foreign keys in the same way as primary keys are. The foreign key is simply a way of telling the Access program how you want information to link together. Generally, there is a natural link field between tables and it is generally best to create the link, and to make the link as strong as the situation calls for or allows.

As you may already know, the link is specified by going to relationships view and dragging a primary key onto the field to relate to and this action creates and specifies the foreign key.

However, if you name the two fields to be lined with the same name and they have the same data type, Access will create the link automatically in the absence of any other between the two tables, so here is a case where you do not have to specify.

In addition to this there are special situations where you do not want any links at all between two tables. For example when you want to create what I call a user held parameter value, which is a technique that begins with adding a repeated value against every record and suing tow tables in q query with no links in the query.

I hope this was of some help, --Regards, Mark

Dear Mark

Thank you for your input.

It was beuatifully explained!!

Many thanks

MOS Master Instructor 2000/2003
MCAS Master Instructor 2007