This article was previously published under Q142567
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In a one-to-many relationship, you can filter child records displayed in agrid by using the Value property of a combo box. One method is to use theRelationalExpr and LinkMaster properties of a grid. This article gives youanother method, which uses a SET FILTER command along with a SELECT-SQLstatement as the row source of a combo box.
To filter the records from the child grid, use the related field from theparent table as the RowSource of a combo box, and use the SET FILTERcommand.
Create a new form by typing the following command in the Command window:
CREATE FORM <form name>.
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 combo box:
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:
SELECT ORDERS THISFORM.MVAR=THIS.VALUE SET FILTER TO CUST_ID = THISFORM.MVAR GO TOP THISFORM.Grid1.RecordSource=THISFORM.Grid1.RecordSource
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 totake advantage of the Rushmore technology.