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Q136994: PRB: Read-Only Recordset with Microsoft SQL Server

Article: Q136994
Product(s): Microsoft C Compiler
Version(s): winnt:2.0,2.1,2.2,4.0,4.1,4.2,5.0,6.0,7.0
Operating System(s): 
Keyword(s): kbusage kbDatabase kbMFC kbODBC kbVC
Last Modified: 06-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2, 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
- Microsoft SQL Server versions 6.0, 7.0 
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SYMPTOMS
========

Microsoft SQL Server versions 6.0 and 6.5 support dynasets. To use an updatable
dynaset, you must have a unique index on one or more fields in the table. If
there is no such index, the recordset will be read only. Also,
CRecordset::CanAppend() and CRecordset::CanUpdate() will return FALSE.

STATUS
======

This behavior is by design.

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

If you create a dynaset without specifying a unique index on one or more fields
in the table and then try to update or add a record, MFC will throw an exception
that says the cursor is read-only. Additionally, you will see the following
errors in the MFC Trace output:

In Visual C++ version 1.5x:

  Cursor is read-only State:S1009[Microsoft][ODBC SQL Server Driver][SQL
  Server] Warning: 0 rows affected by update operation (expected 1). No rows
  were affected by the update or delete operation.

In Visual C++ version 2.x and 4.x:

  Error: failure updating record. Cursor is read-only
  State:S1009,Native:16929,Origin:[Microsoft][ODBC SQL Server Driver] [SQL
  Server]

In Visual C++ 5.0, you will see:

  Cursor concurrency changed State:01S02, Native:0, Origin: [Microsoft][ODBC
  SQL Server Driver] Warning: Concurrency changed by the driver. Marking
  CRecordset as not updatable. Recordset is read-only.

Note that if you use the PRIMARY KEY specification new to SQL Server version 6.0
when creating your tables, you will automatically generate a unique index on the
primary key. Here is an example of this syntax:

        CREATE TABLE Table1
           (cola CHAR(8) PRIMARY KEY NOT NULL,
           colb CHAR(8))

If you are using the Microsoft SQL Server ODBC driver, version 2.65.0201, that
comes with SQL Server version 6.5, MFC will throw an exception that says:

  "Invalid argument value"

Additionally, you will see the following errors in the MFC Trace output:

  Error: failure updating record. Invalid argument value
  State:S1009,Native:0,Origin:[Microsoft][ODBC SQL Server Driver]

Additional query words: CanUpdate CanAppend kbvc151 kbvc152 kbvc200 kbvc210 kbvc220 kbvc400 kbvc500 kbvc600

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Keywords          : kbusage kbDatabase kbMFC kbODBC kbVC 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:2.0,2.1,2.2,4.0,4.1,4.2,5.0,6.0,7.0
Issue type        : kbprb

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