In a one-to-many relationship, you can filter child records displayed in a
grid by using the Value property of a combo box. One method is to use the
RelationalExpr and LinkMaster properties of a grid. This article gives you
another method, which uses a SET FILTER command along with a SELECT-SQL
statement as the row source of a combo box.
To filter the records from the child grid, use the related field from the
parent table as the RowSource of a combo box, and use the SET FILTER
- Create a new form by typing the following command in the Command window:
- Open the Data Environment, and add the Customer and Orders tables from
the Testdata.dbc database located in the Vfp\Samples\Data subdirectory
for Visual FoxPro 5.0 or home(2)+"data" for Visual FoxPro 6.0.
- From the Form menu, choose New Property, and in the Name box, type MVAR.
Then click OK.
- Set the Properties window to the Form1 object. The MVAR property will
be located at the bottom of the list on the All tab. Set the value of
MVAR to "". This will initalize MVAR to a Character Data Type.
- Drag the Orders table to the form to create a grid. Change the name
property of the grid to Grid1.
- Place a combo box on the form after selecting it from the Form Controls
toolbar. Type the following statement in the RowSource property for the
SELECT CUST_ID FROM CUSTOMER INTO CURSOR TEMP
- Choose 3-SQL Statement in the RowSourceType property.
- Open the Code window for the combo box, and add the following code to
its InteractiveChange event:
SET FILTER TO CUST_ID = THISFORM.MVAR
- Save and run the form. When you select an item from the combo box, the
grid should refresh and display the related child records.
NOTE: An index must exist on the filtered field from the child table to
take advantage of the Rushmore technology.
Article ID: 142567 - Last Review: February 12, 2007 - Revision: 4.4
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