Microsoft Office Tutorials and References
In Depth Information
Indexing Fields
To select multiple rows to create a multiple-field primary key, click the
first record selector and then Ctrl+click the record selectors you want
for any additional fields.
3. Click the Primary Key button on the Design tab of the Ribbon, or
right-click the row selector and choose Primary Key from the
contextual menu.
Access displays the key symbol in the record selector for the field.
If you already have data in the field, and two records have the same
value, you can’t make the field the primary key for the table.
The primary key field has to uniquely identify each record.
Indexing Fields
When you index a field, Access sorts and finds records faster by using the
Index field. An index can be based on a single field or on multiple fields. The
primary key field in a table is indexed automatically, and you can choose
other fields to index as well.
Although indexing speeds many operations, it slows some action queries
because Access may need to update the indexes as the action is performed.
To index a field, choose one of the Yes values for the field’s Indexed
property. Three values are available for the Indexed property:
No: Doesn’t index the field.
Yes (Duplicates OK): Indexes the field and allows you to input the
same value for multiple records.
Yes (No Duplicates): Indexes the field and doesn’t allow you to
input the same value for more than one record. The primary key
automatically gets this value.
You can see details of the indexed fields by clicking the Indexes button on the
Design tab of the Ribbon to display the Indexes window, shown in Figure 2-2.
Figure 2-2:
The Indexes
window.
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