Need for relationships

[Ramesh]

Hi,

What are the exact situations where relationships need to be defined? I had
a db with around 15 tables with various relationships setup. I imported all
the tables, queries and forms to another database, as suggested for security
reasons. Now in the new database, none of the old relationships show on the
screen. But all the queries and forms work fine as before.

Question I am left with is are these queries working without the
relationships in place? Then why did i need to create them in the old
database?

should i re create all the relationships again in the new database?

Thanks for some enlightenment here.
Ramesh

 

[Allen Browne]

Relationships with referential integrity ensure your database doesn't finish
up with meaningless orphaned records.

Open the Northwind sample database.
The Relationships window shows a relation between Customers and orders.
If the relation was not there, you could have an order for customer 'AAAA',
and then delete the customer. The order is invalid, but it's still allowed.
Similarly you could change the customer's code to 'BBBB'. The order still
refers to 'AAAA', so it's invalid.

For more info, see:
Referential Integrity can't be that easy!
at:
http://allenbrowne.com/xbase-07.html

 

[Ramesh]

Ok got it Allen. Queries still work as long as the tables are joined in the
query. But data integrity requires relationshiops to be in place.

Hope i have got it right.

Thanks very much.
Ramesh

 

[Allen Browne]

Yep: that's correct.