Microsoft OLE DB Provider for Visual
FoxPro 8.0 Readme
This document contains the most recent notes from the Microsoft Visual FoxPro product
team and has more updated information than the online help documentation. For
information about new features since previous versions of the Provider, see "What's New
in Microsoft OLE DB Provider for Visual FoxPro 8.0”.
For the latest information about the Microsoft OLE DB Provider for Visual FoxPro,
please visit the Visual FoxPro home page at http://msdn.microsoft.com/vfoxpro.
1.1 Important Pre-Installation Information
Installing the Microsoft OLE DB Provider for Visual FoxPro 8.0 on a computer that has a
previous version of the Provider causes this version to replace the previous version. If
you wish to preserve the previous version of the Provider, you must rename it before
proceeding with this installation. To rename the Provider using Windows Explorer:

Shut down any applications that might be using the provider, such as IIS, or any
desktop applications that use the provider.

Open the ...\Program Files\Common Files\System\Ole DB folder

Right click on vfpoledb.dll, select Rename, and change the name to
vfpoledb_save.dll.

To restore the saved version, delete or rename this release version, and rename
vfpoledb_save.dll to vfpoledb.dll. It should not be necessary to re-register the
provider, provided that you have not uninstalled the previous version.
1.2. System Requirements
The Visual FoxPro Ole DB Provider has the following minimum system requirements:

Processor
Pentium class

RAM

Available Hard Disk Space

Operating System Microsoft Windows XP, Microsoft Windows 2000 Service
Pack 2 and later, Windows Me, or Windows 98

Software Microsoft Data Access Components (MDAC) version 2.6 or higher.
64 MB (recommended: 128 MB or higher)
2 MB for minimum install, 4 MB for full install
Note Installation on Windows NT 4.0 is not supported.
2. Known Issues
This section lists known issues in this release of the Microsoft OLE DB Provider for
Visual FoxPro.
2.1. New or Altered Functionality
The following items involve new behavior or behavior changes that might affect the way
your applications behave.

SYS(3099) – For this version, several changes have been made to the Visual
FoxPro SQL engine. The effect of these changes is that certain SQL syntax that
was accepted in version 7.0 will no longer work in 8.0. In those cases where you
wish to continue using the discontinued syntax, the SYS(3099) function was
added:

SYS(3099, 70) && Version 7 compatibility

SYS(3099, 80) && Version 8 compatibility (default)

To set this value in the provider, execute the function with the desired
parameter. You may also use this function in stored procedures to set the
SQL compatibility level as appropriate. A summary of changes follows.

Using the DISTINCT clause in a SELECT SQL statement containing
Memo and/or General fields is no longer supported. Instead, you can wrap
a Memo field expression inside a function such as PADR() or
ALLTRIM(). Additionally, you can no longer use a UNION clause with a
Memo field unless the ALL clause is also included. An error is now
generated if a Memo or General field is used in this scenario.
ex. SELECT DISTINCT * FROM Labels
Labels.dbf contains a Memo field

&& now fails since the
The handling of the GROUP BY clause (and related HAVING clause) has
changed. For example, version 7.0 allows for the following syntax:
ex. SELECT cust_id, country FROM Customer GROUP BY country
This statement can lead to ambiguous results since one of the fields
(cust_id) is not specified in the GROUP BY clause. In Version 8, we will
now raise an error like SQL Server. Note: you can include an Aggregate
function in the field list without having it in the GROUP BY clause.
ex. SELECT COUNT(cust_id), country FROM Customer GROUP BY
country
In addition, Memo and General fields are not supported in GROUP BY
unless used in an expression:
ex. SELECT last_name,LEFT(notes,100) AS notes2 from employee
GROUP BY last_name, notes2

The following new functionality may be set in the Config.fpw FoxPro
configuration file (the Config.fpw file placed must be placed in the same directory
as the Provider):

ENGINEBEHAVIOR – Specifies the Engine compatibility level. Note
that this command is the same as SYS(3099), but is settable in the
Config.fpw configuration file.

Example: Specifies that Visual FoxPro treats SQL SELECT
commands as it did in versions prior to Visual FoxPro 8.0.


Specifies that Visual FoxPro treats SQL SELECT commands as
follows. (Default)


Example: TABLEVALIDATE=<nLevel>

nLevel specifies the table validation level. If omitted, the
default value of nLevel is 3. The following lists the values
for nLevel:

0 - Does not perform table validation.

1 - Validate record count when opening a table.
Note: The table (.dbf) file header is locked during
validation. This can result in decreased scalability
when tables are opened as shared, for example, by
calling USE tableName SHARED, or when calling
a SQL SELECT, INSERT, UPDATE, or
DELETE command for an unopened table, and
SET EXCLUSIVE is OFF.

2 - Validate record count when appending or
inserting records and writing them to disk.

3 - Validate as described by nLevel=1 and
nLevel=2. (Default)
The following configuration setting is also now supported in the
Config.fpw file:

MVCOUNT - sets the maximum number of variables that Visual
FoxPro Provider can maintain (in stored procedures). For more
information, see "Special Terms for Configuration Files" topic on
MSDN. Note that the default MVCOUNT has been increased to
16384.


ENGINEBEHAVIOR=80
TABLEVALIDATE - Specifies the level of table validation to perform.
You can use TABLEVALIDATE when you want a lower level of table
integrity checking than the default setting.


ENGINEBEHAVIOR=70
Example: MVCOUNT=32768
Note that only the above three FoxPro configuration file settings are
recognized by the Provider when reading the Config.fpw file.

When setting the connection string for the Visual FoxPro OLE DB Provider, you
can specify an existing Visual FoxPro ODBC Data Source Name (DSN) instead
of a data source. The Provider uses the data source indicated in the DSN and
expands it to an appropriate Provider connection string. For example, if there is an
existing DSN named "VFP_Northwind", you can connect using the following
connection string: "Provider=VFPOLEDB.1; DSN=VFP_Northwind;"

The GETENV( ) function is no longer supported in the OLE DB Provider.

Stored Procedures may be called in two ways:

myProc( param1, param2, …)
FoxPro calling syntax.

Exec myProc param1, param2, … && Alternate syntax. Note that when
using ADO or ADO .NET, and setting the CommandType to StoredProc,
this form is required.
&& This is the conventional Visual
o When using the CommandType of StoredProcedure in ADO.NET,
you must do one of the following or it will fail:
1. Set the CommandText to the name of the stored procedure
without any parentheses. Then add the parameters to the
Parameters collection.
2. Set the CommandText to the name of the stored procedure
with the parameters included in the parentheses like the
conventional Visual FoxPro calling syntax. You then can
not use the Parameters collection to store the parameter
values.
o When using the CommandType of StoredProc in ADO:
1. Set the CommandText to the name of the stored procedure
with parentheses and place holders (?) for each parameter
sent. Then create parameters objects for each one used in
the place holders.
2. Set the CommandText using the conventional Visual
FoxPro calling syntax.

Also note that that the "EXEC" key word is automatically supplied by
ADO and ADO .NET and is not required unless the CommandType is
other than StoredProc.
2.2. Documentation Issues
Please refer to the "What's New in Visual FoxPro 8.0" topic for a complete list of all new
features.
2.3. Feature Issues
This section describes the most recent information about feature issues included in this
release of Visual FoxPro.

When you "drag-and-drop" tables from the Visual Studio .NET Server Explorer to
the VS IDE Design Surface, you may have to make changes to the generated
SelectCommand – i.e.; remove the double quotes, or enter the appropriate VFP
SQL statement via ConfigureDataAdapter. The DataWizard will not currently
create the Update/Insert/Delete statements – you must configure these yourself.

When used with SQL Server as a "linked server", the Provider supports query
operations only. The Provider does not support update operations
(Update/Insert/Delete).

Using the DISTINCT clause in a SELECT SQL statement containing Memo
and/or General fields is no longer supported. Instead, you can wrap a Memo field
expression inside a function such as PADR() or ALLTRIM(). Additionally, you
can no longer use a UNION clause with a Memo field unless the ALL clause is
also included. An error is now generated if a Memo or General field is used in this
scenario. See the SYS(3099) topic in "New or Altered Functionality" in this
readme for additional details.

When passing a table name only to the provider via ADO, you must set the
CommandType to adCmdTable.
2.4. Resolved Issues
Following is a list of articles from the Microsoft knowledge base listing problems with
the current, released version of the VFP provider (versions 7.0.0.9262 and 7.0.0.9465).
These problems are resolved in this web release version of the provider:
BUG: VFP OLE DB Provider Only Works with CHAR Command Parameters
http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q321631
BUG: Error Selecting Empty VFP Memo w/ .NET OleDbDataAdapter
http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q326544
.