Databases and Access by: bs0d

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RELATIONSHIPS:

FORMATTING A CALCULATED FIELD

1. Click on the PROPERTIES icon on the tool bar.
2. Click on FORMAT tab.

TYPES OF RELATIONSHIPS...

• ONE TO ONE -one group of data can be related to one and only one other group of data. When creating a one-to-one relationship, you are going from the key field of one table to the key-field of another table. An example of a one-to-one relationship would be student to student-id.
• ONE TO MANY - one group of data can be related to one or more other groups of data but the reverse is not true. When creating a one-to-many relationship, you are going from the key field of one table to a corresponding field in the second table where the field in the second table is not a primary key. An example of a one-to-many relationship is a mother to her children.
• MANY TO MANY -one group of data can be related to one or more other groups of data and vice versa. When creating a many-to-many relationship, it takes two one-to-many relationships put together. An example of a many-to-many relationship would be uncles to nephews.
• REFERENTIAL INTEGRITY -A system of rules in Access that ensures that relationships between records in related tables are valid and that you don’t accidentally delete or change related data. Referential integrity ensures that for each record in one table, there is at least one matching record for it in the second table.
• ORPHANS - records in the first table that do not have matching records in the second table or vice versa.

Conclusion

People literally write books on this, and go into full detail. This I believe is detailed enough for you to get the understanding of Databases and Microsoft Access. Hopefully after reading this tutorial, you will have learned something, and will go on to creating your own successful databases and discover new things and so on. I recommend in many cases just opening the program and exploring around. Combine that with this tutorial and you should have a great start.