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The All-Important Primary Key
The most important index in a table is called the Primary Key index; it ensures uniqueness of the fields that make up the index and also gives the table a default order. You must set a primary key for the fields on the one side of a one-to-many relationship. To create a Primary Key index, select the fields you want to establish as the primary key, then click the Primary Key button on the toolbar.Figure 2.20 shows the tblCustomer table with a Primary Key index based on the CompanyID field. Notice that the Index Name of the field designated as the primary key of the table is called PrimaryKey. Note that the Primary and Unique properties for this index are both set to Yes (true).
Figure 2.20. A Primary Key index based on the CompanyID field.
