wHEN IS THE BEST TIME TO USE 1 TO 1 RELATIONSHIPS

Hi Andrew, Thank you for the post, in answer to your question;
A one-to-one relationship exists where for every one record in the primary table there is one and only one matching record in another table i.e. a table comprising employee information and a table comprising salary information may be created because each employee has only one entry in the salaries table.

This form of relationship is used in the following scenarios:
1. Security – create separate tables when one contains information that should be freely available, and the other confidential information that needs to be secured i.e. employee records.
2. Data in tables is updated by different departments.
3. If you need more fields than the maximum number allowed (255), extra fields can be added into another table and the two can be linked via a one-to-one relationship.
In this type of relationship, it does not matter which is the primary table, unless referential integrity is enforced.
I hope that has helped, if so please click the resolved button, best regards Pete.