DOCUMENT:Q191522 22-FEB-2000 [foxpro]
TITLE :FIX: TABLEUPDATE() Fails in Remote View With Empty Memo Field
PRODUCT :Microsoft FoxPro
PROD/VER:WINDOWS:2.5,3.0,5.0
OPER/SYS:
KEYWORDS:kbMDAC250
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The information in this article applies to:
- Microsoft ODBC Driver for Visual FoxPro, versions 3.0, 5.0
- Microsoft Data Access Components version 2.5
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SYMPTOMS
========
You have a remote view to a Visual FoxPro table using the Visual FoxPro ODBC
driver. When you attempt to issue a TABLEUPDATE() after replacing a memo field
value with an empty string (""), the TABLEUPDATE() fails with the following
error:
Connectivity error: [Microsoft][ODBC Visual FoxPro Driver]Invalid string or
buffer length.
NOTE: This may also happen connecting through the Visual FoxPro ODBC driver from
other clients such as MSQuery.
RESOLUTION
==========
As a workaround, you can set the field to accept NULL values and replace the
field value with NULL rather than "".
STATUS
======
Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been corrected in Visual FoxPro 6.0.
MORE INFORMATION
================
Steps to Reproduce Behavior
---------------------------
1. Run the following code from a program (.PRG) file. It programmatically
creates an ODBC User DSN called "VFP TestDB" to connect to a database
container called TestDB.dbc. The .dbc is created, a table called TESTTAB is
created, and a remote view (called TESTTAB_REMOTE) to that table is created.
The view is USEd, the Notes memo field is replaced with the value "", and the
TABLEUPDATE() is issued. TABLEUPDATE() returns .F. and the error generated
is:
Connectivity error: [Microsoft][ODBC Visual FoxPro Driver]Invalid string or
buffer length.
LOCAL lcDir, lcSettings, laErrorArray[1]
CLEAR
SET EXCLUSIVE OFF
CLOSE DATABASE ALL
* Declare API function to create ODBC User DSN.
DECLARE INTEGER SQLConfigDataSource IN odbccp32.DLL ;
INTEGER, INTEGER, STRING, STRING
lcDir = SET('DEFAULT')+CURDIR()
lcSettings="DSN=VFP TestDB"+CHR(0)+;
"Description=VFP TestDB"+CHR(0)+;
"SourceDB="+lcDir+"testdb.dbc"+CHR(0)+;
"SourceType=DBC"
* Call API function to create ODBC User DSN.
=SQLConfigDataSource(0,1,"Microsoft Visual FoxPro Driver",lcSettings)
SET SAFETY OFF
* Make the database.
CREATE DATABASE 'TESTDB.DBC'
* Make the table and index.
CREATE TABLE 'TESTTAB.DBF' NAME 'TESTTAB' (PK C(5) NOT NULL, ;
NOTES M NOT NULL)
ALTER TABLE 'TESTTAB' ADD PRIMARY KEY PK TAG PK
CLOSE DATABASE ALL
OPEN DATABASE testdb SHARED
* Make the remote view.
CREATE SQL VIEW "TESTTAB_REMOTE" ;
REMOTE CONNECT "VFP TestDB" ;
AS SELECT * FROM TESTTAB Testtab
* Set the view properties.
DBSETPROP('TESTTAB_REMOTE', 'View', 'UpdateType', 1)
DBSETPROP('TESTTAB_REMOTE', 'View', 'WhereType', 1)
DBSETPROP('TESTTAB_REMOTE', 'View', 'FetchMemo', .T.)
DBSETPROP('TESTTAB_REMOTE', 'View', 'SendUpdates', .T.)
DBSETPROP('TESTTAB_REMOTE', 'View', 'UseMemoSize', 255)
DBSETPROP('TESTTAB_REMOTE', 'View', 'FetchSize', 100)
DBSETPROP('TESTTAB_REMOTE', 'View', 'MaxRecords', -1)
DBSETPROP('TESTTAB_REMOTE', 'View', 'Tables', 'TESTTAB')
DBSETPROP('TESTTAB_REMOTE', 'View', 'Prepared', .F.)
DBSETPROP('TESTTAB_REMOTE', 'View', 'CompareMemo', .T.)
DBSETPROP('TESTTAB_REMOTE', 'View', 'FetchAsNeeded', .F.)
DBSETPROP('TESTTAB_REMOTE', 'View', 'FetchSize', 100)
DBSETPROP('TESTTAB_REMOTE', 'View', 'Comment', "")
DBSETPROP('TESTTAB_REMOTE', 'View', 'BatchUpdateCount', 1)
DBSETPROP('TESTTAB_REMOTE', 'View', 'ShareConnection', .F.)
* Set the view field properties.
DBSETPROP('TESTTAB_REMOTE.pk', 'Field', 'KeyField', .T.)
DBSETPROP('TESTTAB_REMOTE.pk', 'Field', 'Updatable', .T.)
DBSETPROP('TESTTAB_REMOTE.pk', 'Field', 'UpdateName', 'TESTTAB.pk')
DBSETPROP('TESTTAB_REMOTE.pk', 'Field', 'DataType', "C(5)")
DBSETPROP('TESTTAB_REMOTE.notes', 'Field', 'KeyField', .F.)
DBSETPROP('TESTTAB_REMOTE.notes', 'Field', 'Updatable', .T.)
DBSETPROP('TESTTAB_REMOTE.notes', 'Field', 'UpdateName', ;
'TESTTAB.notes')
DBSETPROP('TESTTAB_REMOTE.notes', 'Field', 'DataType', "M")
SET SAFETY ON
* Add a couple of records to the table.
INSERT INTO TESTTAB VALUES ("A", "1234567890")
INSERT INTO TESTTAB VALUES ("B", "1234567890")
CLOSE DATABASE ALL
OPEN DATABASE testdb
* Open the view.
USE testdb!TESTTAB_remote
*Replace field with "" and issue TABLEUPDATE()
REPLACE NOTES WITH ""
IF !TABLEUPDATE(.T.)
?"Tableupdate failed with the following error:"
=AERROR(laErrorArray)
?laErrorArray(2)
=TABLEREVERT()
ENDIF
TABLEUPDATE() returns .F. indicating that it failed. The error returned from
AERROR() is:
Connectivity error: [Microsoft][ODBC Visual FoxPro Driver]Invalid string or
buffer length.
If the memo field is set to accept nulls and the REPLACE replaces the value with
NULL, the error does not occur. You can do the following within Visual FoxPro:
You can demonstrate this by changing the preceding CREATE TABLE line to read:
CREATE TABLE 'TESTTAB.DBF' NAME 'TESTTAB' (PK C(5) NOT NULL, ;
NOTES M NULL)
-and- change the REPLACE line to read:
REPLACE NOTES WITH NULL
To employ this workaround from within a Visual FoxPro form, for instance, make
the following changes:
1. Set the following environment setting in Visual FoxPro 5.0. This makes the
NULL display as an empty string.
SET NULLDISPLAY TO ""
2. In an Editbox Valid method, you could add the following code to ensure that
the NULL is used if the Value property of the Editbox is empty:
IF EMPTY(This.Value)
This.Value = NULL
ENDIF
REFERENCES
==========
Visual FoxPro Help; search on: "DECLARE - DLL"; "CREATE TABLE - SQL"; "SET
NULLDISPLAY"
(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Jim
Saunders, Microsoft Corporation
Additional query words: kbVFp300bbug kbVFp500abug kbVFp600bug kbODBC
======================================================================
Keywords : kbMDAC250
Technology : kbVFPsearch kbAudDeveloper kbODBCSearch kbMDACSearch kbMDAC250 kbODBCVFP300 kbODBCVFP500
Version : WINDOWS:2.5,3.0,5.0
Issue type : kbbug
Solution Type : kbfix
=============================================================================
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