The Relationships Screen

The relationships screen serves two functions.

1. It allows you to pre-define relationships between tables prior to producing a new query. When you start inserting tables into the new query, the joins (relationships) between the tables will be inherited from that defined in the relationships screen. You can of course opt to remove the relationships for that particular query.
   
2. It allows you to define referential integrity rules between tables.

The two functions, although they share the same screen, use different (but overlapped) options on the screen.

Referential Integrity Options

Combination 1

• If a parent record has associated child records, you cannot simply delete the parent record. You have to go to the child table, delete the associated records and then come back and delete the parent record.
  
• If the parent record has associated child records, you cannot simply change the participating key of the parent record. You will have to move the child records to a temporary table, change the parent key, change the associated values in the child records which are in the temporary table and then append back the child records.

Combination 2

Combination 3

Combination 4