Primary Property

Applies To

Index, Index Object.

Description

You can use the Primary property to specify whether the index is the primary key for the table. A primary key uniquely identifies each record in a table and prevents you from entering duplicate values in a primary key field.

Setting

The Primary property uses the following settings.

Setting

Description

Visual Basic

Yes

The selected index is the primary key.

True (-1)

No

The selected index isn’t the primary key.

False (0)


You can set the Primary property in three ways:

  • In table Design view, select the field or fields in the order you want for the primary key and then click Primary Key on the Edit menu or click the Primary Key button on the toolbar.
  • In the Indexes window, select or enter the name of an index in the Index Name column and set the Primary property to Yes in the Index Properties list.
  • In Visual Basic to access the Primary property of an index in Visual Basic, use the Data Access Objects Primary property.

Remarks

Microsoft Access creates an index on the primary key of the table and uses it to find records and to create joins between tables. The primary key index requires an entry in each primary key field and allows no duplicates. The order of the fields determines the default sort order for the table.

If there is no primary key when you save a table design, Microsoft Access will display a dialog box asking whether you want a primary key to be created. If you choose Yes, an AutoNumber data type field will be added to the table (with its NewValues property set to Increment) and set as the primary key. If you choose No, no primary key will be created.

A table with no primary key can’t be used in a relationship and can be slower to sort and search.

See Also

Indexed Property, Primary Property (Microsoft Office 95 Data Access Reference), Unique Property.