Latest revision as of 11:07, 21 July 2020

Knowledge Base

BUG: Scrolling in a grid may be slow if you use a filtered cursor in Visual FoxPro for Windows

Article ID: 174584

Article Last Modified on 3/11/2005

APPLIES TO

Microsoft Visual FoxPro 3.0 Standard Edition
Microsoft Visual FoxPro 3.0b Standard Edition
Microsoft Visual FoxPro 5.0 Standard Edition
Microsoft Visual FoxPro 5.0a
Microsoft Visual FoxPro 6.0 Professional Edition

This article was previously published under Q174584

SYMPTOMS

Scrolling in a grid might be slow if the RecordSource of the grid points to a cursor, which actually is a filter of the table.

RESOLUTION

Use the following steps to work around the problem:

Use the SET KEY TO command to filter the data instead of using a SELECT-SQL command.

For example if you wanted to find all the records that have CA for the region field, use the following code:
```
      SET ORDER TO xregion
      SET KEY TO "CA"
                        
```
This is assuming that there is a index tag on the region field called "xregion."
Use the NOFILTER clause in the SELECT-SQL statement to ensure that the cursor created will not be a filter. This clause is only valid in Visual FoxPro 5.0. In Visual FoxPro 3.0 you can add a ".T." to the field list to prevent the filter. For example:
```
      SELECT *,.t. FROM Customer WHERE country = "USA" INTO CURSOR test
                        
```

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

This problem occurs only with cursors created with the SQL SELECT command. A local view will not create a filtered cursor.

Steps to Reproduce Behavior

Use a large table with more than 200,000 records.

Create a simple SELECT-SQL statement such as the following:

      SELECT * FROM Customer WHERE country = "USA" INTO CURSOR test

Create a form with a grid on it.
Set the RecordSource property of the grid to the cursor test.
Run the form.
Drag the scroll button of the grid all the way to the bottom.

Keywords: kbprb KB174584

@@ Line 63: / Line 63: @@
 For example if you wanted to find all the records that have CA for the region field, use the following code:</p>
 <pre class="codesample">      SET ORDER TO xregion
-       SET KEY TO &quot;CA&quot;
+       SET KEY TO "CA"
                          </pre>
-<p>This is assuming that there is a index tag on the region field called &quot;xregion.&quot;</p></li>
+<p>This is assuming that there is a index tag on the region field called "xregion."</p></li>
-<li><p>Use the NOFILTER clause in the SELECT-SQL statement to ensure that the cursor created will not be a filter. This clause is only valid in Visual FoxPro 5.0. In Visual FoxPro 3.0 you can add a &quot;.T.&quot; to the field list to prevent the filter. For example:</p>
+<li><p>Use the NOFILTER clause in the SELECT-SQL statement to ensure that the cursor created will not be a filter. This clause is only valid in Visual FoxPro 5.0. In Visual FoxPro 3.0 you can add a ".T." to the field list to prevent the filter. For example:</p>
-<pre class="codesample">      SELECT *,.t. FROM Customer WHERE country = &quot;USA&quot; INTO CURSOR test
+<pre class="codesample">      SELECT *,.t. FROM Customer WHERE country = "USA" INTO CURSOR test
                          </pre></li></ol>
@@ Line 89: / Line 89: @@
 <li>Use a large table with more than 200,000 records.</li>
 <li><p>Create a simple SELECT-SQL statement such as the following:</p>
-<pre class="codesample">      SELECT * FROM Customer WHERE country = &quot;USA&quot; INTO CURSOR test
+<pre class="codesample">      SELECT * FROM Customer WHERE country = "USA" INTO CURSOR test
                          </pre></li>
 <li>Create a form with a grid on it.</li>

Microsoft KB Archive/174584: Difference between revisions