Relational databases

Practical definition: Organized collection of data stored in logically related tables.

Example:

1. Open the Northwind training database in MS Access 2003 (C:\TEMP\NorthwindTraining.mdb in 116 PHTC)  by double-clicking on the file name or by opening MS Access from the Start menu and locating the database under File/Open.  The database opens behind a "splash screen":

(NOTE: For practice on your own computer, make a copy of the Northwind database before starting; or start in a blank new database and import the Northwind tables you need.)

2. Close the splash screen by clicking OK.  The Main Switchboard form becomes visible in front of the database window:

3.  Close the Main Switchboard by clicking on Display Database Window.  Verify that "Tables" is selected in the Objects bar on the left.

4. Double-click on the Products table to see the data (open it in Datasheet view, in MS Access terminology).  A partial view:

5. Change to table Design view by clicking on the View button (circled above) and find the primary key.  To check for other indexed columns, select Indexes from the View menu:

6. Close the table

Referential integrity constraints: Primary / foreign key relationships or rules defined using SQL or vendor extensions that prevent loss or unwanted modification of data and maintain data consistency throughout all tables in the database.

Example: Relationships diagram in the Northwind database

1. Click the Relationships button (circled below) or choose Tools / Relationships:

The relationships window opens:

2. Find the Products table and its related table or tables.

3. Note the primary key (ProductID) and two foreign keys (SupplierID and CategoryID) in the Products table.