ACC2000: AutoLookup Query Not Performed with a One-to-One Relationship

ID: Q208916

The information in this article applies to:

Microsoft Access 2000

Advanced: Requires expert coding, interoperability, and multiuser skills.

SYMPTOMS

Microsoft Access does not perform an AutoLookup query if it determines that the tables in the query have a one-to-one relationship.

CAUSE

Access determines the relationship between the tables in the query by examining the indexes on the join fields. Access ignores the relationship that you specify when it is determining whether to perform an AutoLookup query. If your tables have one of the following index combinations, Access does not perform an AutoLookup query:


   Table 1                  Table 2
   ----------------------   ----------------------
   Primary Key              Primary Key
   Primary Key              Indexed, No Duplicates
   Indexed, No Duplicates   Primary Key

RESOLUTION

To cause Access to perform an AutoLookup query, make sure the foreign key is neither indexed as the Primary Key nor as Indexed, No Duplicates. You may have to add a unique index to the foreign key on the "many" side of a relationship in order to maintain the integrity of the data.

MORE INFORMATION

Consider the following tables:


   Table: Employees
   ----------------------------
   Field Name: EmployeeID 
   Data Type: AutoNumber
   Indexed: Yes (No Duplicates)

   Field Name: LastName
   Data Type: Text

   Table Properties: Table1
   -------------------------------
   PrimaryKey: Category ID
   Index1: Category Name; Location


   Table: Offices
   ----------------------------
   Field Name: OfficeID 
   Data Type: AutoNumber
   Indexed: Yes (No Duplicates)

   Field Name: AssignedTo
   Data Type: Text

   Table Properties: Table1
   -------------------------------
   PrimaryKey: Category ID
   Index1: Category Name; Location

To ensure that an employee is not assigned to more than one office, add a unique index to the Offices.[AssignedTo] field. It doesn't matter whether there is no relationship, a one-to-many relationship, or a one-to-one relationship defined between these tables; Access determines that the relationship is one-to-one when determining whether to perform an AutoLookup query.

Steps to Reproduce Behavior

CAUTION: Following the steps in this example will modify the sample database Northwind.mdb. You may want to back up the Northwind.mdb file and perform these steps on a copy of the database.

Open the sample database Northwind.mdb and create the following new table:


   Table:  Offices
   ------------------------
   FieldName: OfficeID
   Data Type: AutoNumber
   Field Size: Long Integer
   New Values: Increment

   FieldName: Building
   Data Type: Text

   FieldName: AssignedTo
   Data Type: Number
   FieldSize: Long Integer
   DefaultValue: <blank>

Click the OfficeID field, and then click Primary Key on the Edit menu.

View the table in Datasheet view, and then add the following data to the table:


   OfficeID   Building   AssignedTo
   --------------------------------
       1          A
       2          A
       3          B

Create a new query based on the Employees and Offices tables.

Join the tables on the Employees.[EmployeeID] and Offices.[AssignedTo] fields.

Drag all the fields from the Offices field list to the query design grid, and then drag the FirstName and LastName fields from the Employees field list to the query design grid.

Run the query. Type 7 in the AssignedTo field, and then press ENTER. Note that the AutoLookup query fills in the FirstName and LastName fields for the record.

Save the query as AssignOffices, and then close it.

Open the Offices table in Design view.

Set the Indexed property of the AssignedTo field to Yes (No Duplicates).

Save the table and close it.

Run the AssignOffices query. Type 3 in the first blank AssignedTo field and press ENTER. Note that Access does not fill in the FirstName and LastName fields.

Press SHIFT+F9 to run the query again.

Note that the fields are filled.

REFERENCES

For more information about AutoLookup queries, click Microsoft Access Help on the Help menu, type autolookup queries in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.

Additional query words: row fix-up updateable prb

Keywords : kbdta QryFixup
Version : WINDOWS:2000
Platform : WINDOWS
Issue type : kbprb