Once you have added the necessary key attributes that support relationships, you have arrived at a set of relational tables: the attributes are now columns, and the key values are now key columns. From what has been done so far, you can see a set of relational tables emerging, as follows ( * indicates a key column):
Table 2-2 Columns and Keys for Four Tables
| Albums Table | Selections Table | Composers Table | Log Table |
|---|
| *AlbumCode | *AlbumCode | *ComposerName | *AlbumCode |
| AlbumTitle | *SelectionName | Birth | *SelectionName |
| Medium | ComposerName | Death | StartTime |
| AlbumCost | Timing | Birthplace | EndTime |
| RecordingCo | Performers | Comment | Announcer |
| DateRecorded | | | |
| MfgCode | | | |
| Comment | | | |
Note that the Selections and Log tables each have two key columns, whereas the other tables have only one apiece. Remember that a key must uniquely identify each entry in the table.
