PRB: SET INDEX TO Command Causes Error When Run from a Form

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b

SYMPTOMS

One of the following errors occurs occur when attempting to run the SET INDEX TO command programmatically from a running form:

• File must be opened exclusively.

  -or-

• File is in use by another.

CAUSE

A table opened by the Data Environment of a form is opened shared by default. Therefore, when the form is running and you issue an INDEX ON command, an error occurs.

RESOLUTION

Set the Exclusive Property of the cursor to .T. at design time.

NOTE: Attempting to set this property at run-time causes the following error message:

   Property setting will not take effect until data environment reloaded

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a form.

2. Right-click the form, and then click Data Environment.

3. Right-click the Data Environment window, and then click Add.

4. Locate the Customer table in the Vfp\Samples\Data directory, and then

1. Scroll down in the list box displaying the Customer table and note which

1. Add a command button to the form.

2. Add the following code to the Click method of the command button

        SELECT CUSTOMER
        INDEX ON <field_name> TAG <field_name>
   

   where field_name is the name of a field in the Customer table that does not already have an index tag, as noted earlier in Step 5.

3. Save and run the form.

4. Click the command button.

Steps to Correct Form Created in Previous Example

1. Close, and then edit the form.

2. Right-click the form, and then click Data Environment.

3. Right-click the Customer table list box, and then click Properties.

4. In the Properties window, click the Data tab, and then examine the Exclusive property. Note that the default value is .F.

5. Change the Exclusive value to .T., and then save and rerun the form.