Q165068: PRB: INDEX ON with Variable Length Tag May Behave Differently

Article: Q165068
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): kbvfp
Last Modified: 04-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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SYMPTOMS
========

When attempting to create a variable length index tag in Visual FoxPro version
5.0, one of the following error messages may occur:

  Cannot access characters beyond string

  -or-

  Invalid key length

This behavior does not occur in earlier versions of FoxPro.

According to the Visual FoxPro online Help, variable length index keys are not
supported in Visual FoxPro. As stated in the Help file:

  If you attempt to build an index with a key that varies in length, the key
  will be padded with spaces. Variable-length index keys aren't supported in
  Visual FoxPro.

In the case of Visual FoxPro 5.0, it appears that any variable length key is not
being padded.

RESOLUTION
==========

The following code creates an index tag from a variable length key but is padded
to a specific length:

     SET TALK OFF  && If TALK isn't turned off, an error will occur.
       SET SAFETY OFF
        CREATE TABLE oneproduct ;
             (PRODUCT c(15))
        SET SAFETY ON
        INSERT INTO oneproduct (PRODUCT) VALUES ("01PAN AG-1310")

         INDEX ON PADR(SUBSTR(product, AT(" ", product)+1), ;
            LEN(product)+2 ," ") TAG prod

STATUS
======

Microsoft is researching this behavior and will post new information here in the
Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

The following code illustrates the problem with creating a variable length index
tag:

     SET SAFETY OFF
     CREATE TABLE oneproduct ;
          (PRODUCT c(15))
     SET SAFETY ON
     INSERT INTO oneproduct (PRODUCT) VALUES ("01PAN AG-1310")

     * The following code works without error in versions prior to 5.0
     INDEX ON SUBSTR(PRODUCT,AT(" ",PRODUCT)+1) TAG prod1
     INDEX ON RIGHT(PRODUCT,LEN(PRODUCT)-AT(" ",PRODUCT)) TAG prod2

     * The following code works without error:
     *!*   SET TALK OFF
     *!*   INDEX ON PADR(SUBSTR(product, AT(" ", product)+1), ;
     *!*     LEN(product)+2 ," ") TAG prod

The first INDEX ON line causes the error message,

  Cannot access characters beyond string.

The second INDEX ON line causes the error message,

  Invalid key length.

This behavior does not occur in earlier versions of FoxPro and the indexes are
created without error.

Additional query words: previous kbvfp500

======================================================================
Keywords          : kbvfp 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : WINDOWS:5.0,5.0a
Issue type        : kbprb

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