ACC: Example of Row Fix-Up in the Northwind Orders Form (95643)

MORE INFORMATION

To see an example of the row fix-up technique, follow these steps:

1. Open the Northwind.mdb sample database (or NWIND.MDB in versions 1.x and 2.0).
2. Open the Orders form in Design view.
3. Select the RecordSource property on the Orders form's property sheet and click the Build button. (In Microsoft Access 1.x, open the Order Information query in Design view.) Note the following about the RecordSource property of the Orders form:
   1. In Microsoft Access 97, the record source is the Orders Qry query. In version 7.0, the record source is an SQL Select statement. In version 1.x and 2.0, the record source is the Orders Information query.
   2. The Join property between Customers and Orders tables is:
      
      

               One                          Many
               -------------------------------------------------
               CUSTOMERS.[CustomerID] ==>  ORDERS.[CustomerID]
      							

      
      NOTE: In versions 1.x and 2.0, there is a space in Customer ID field name.
   3. The OrderID field in the query grid comes from the Orders table, which is on the "many" side of the relationship, and not from the Customers table, which is on the "one" side of the relationship. (See point 3b, above.)
      
      NOTE: In versions 1.x and 2.0, there is a space in the Order ID field name.
4. Close the RecordSource query and click the Bill To combo box. Look at its RowSource property on the property sheet. In Microsoft Access 7.0 and 97, the row source is an SQL Select statement. In versions 1.x and 2.0, the row source is based on the Customer List query. Click the Build button and note the following about the RowSource query:
   1. The query is based on the Customers table.
   2. The query returns two columns: CompanyName and CustomerID.
      
      NOTE: In versions 1.x and 2.0, there is a space in Company Name and Customer ID field names.
   3. The bound column is CustomerID.
   4. The visible column is CompanyName.
5. Microsoft Access select queries are updatable. This means that when you make a change to a query's recordset, Microsoft Access can update the source tables with your changes.

The Bill To combo box presents you with a list of company names from the visible column of its RowSource query. When you select a company name, the combo box stores the bound column--the CustomerID field from the RowSource query--in the CustomerID field in the Orders table. (See points 4c and 4d, above.) It is important to note that the selection is stored in the many- side table. (See point 3c, above.)

After the combo box updates the CustomerID field in the Orders table (the many-side table), the field is changed so it no longer points to the same record in the Customers table (the one-side table). (See point 5, above.) Note that the Orders table is updated because the query's recordset was changed.

Microsoft Access recognizes that the relationship no longer matches; therefore, it automatically updates the relationship by linking the changed record in the Orders table with the appropriate record in the Customers table.

All the fields in the Orders form that come from the Customers table (the one-side table) are updated to show the values in the record for the newly formed link.

Example

When you make a change to the Bill To combo box, Microsoft Access uses row fix-up to update the following fields on the Orders form:

• [Address]
• [City]
• [Region]
• [PostalCode]
• [Country]

The following fields on the Orders form are not updated by Row fix-up. However they are updated by the AfterUpdate event attached to the Bill To combo box:

• [ShipName]
• [ShipAddress]
• [ShipCity]
• [ShipRegion]
• [ShipPostal]
• [ShipCountry]