• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Chapter 4. Exploring Relational Database... > Defining the Structure of Relational...

Defining the Structure of Relational Databases

Relational databases consist of a collection of self-contained, related tables. Tables typically represent classes of physical objects, such as customers, sales orders, invoices, checks, products for sale, or employees. Each member object, such as an invoice, has its own record in the invoices table. For invoices, the field that uniquely identifies a record, called a primary key [field], is a serial invoice number.

Figure 4.1 shows Access’s Datasheet view of an Invoices table, which is based on the Northwind.mdb sample database’s Orders table. The InvoiceNo field is the primary key. Values in the OrderID, CustomerID, EmployeeID, and ShipperID fields relate to primary key values in Northwind’s Orders, Customers, Employees, and Shippers tables. A field that contains values equal to those of primary key values in other tables is called a foreign key [field].


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint