Q186198: PRB: ClassWizard Binds Fields in Incorrect Order Causing Errors

Article: Q186198
Product(s): Microsoft C Compiler
Version(s): WINNT:5.0, 6.0
Operating System(s): 
Keyword(s): kberrmsg kbwizard kbDatabase kbMFC kbODBC kbVC500 kbVC600 kbGrpDSTools
Last Modified: 17-JUL-2001

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The information in this article applies to:

- The ClassWizard, included with:
   - 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 
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SYMPTOMS
========

When you use the AppWizard to create a database application that uses the
CRecordset class, fields are listed in the DoFieldExchange function in table
order. However, if you use the ClassWizard to bind columns to variables, the
fields are listed in alphabetical order. The order in which the fields are
listed presents no problem as long as the default SQL statement provided by the
wizard is used.

The default SQL statement is the table name in square brackets and is located
inside the GetDefaultSQL function. Using a statement such as "Select * From
Tablename" can result in errors when the fields are out of order. The errors can
be different, depending on the data types represented by the fields and the
variables they are bound to.

Some possible error messages you might receive because the fields in
DoFieldExchange are out of order are:

- Invalid Character Value for Cast Specification

- Restricted Datatype Attribute Violation

- Error in Assignment on Column Number [x]

- Error Retrieving Record

There may also be other errors depending on the data types involved.

RESOLUTION
==========

If you need to supply a SQL Select statement make sure the items in the
DoFieldExchange function are in the same order as the fields in the select
statement or in table order.

STATUS
======

This behavior is by design.

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

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

1. Create a single document, MFC AppWizard (exe) project. In Step 2 of the
  wizard, choose Database either with or without file support and click
  DataSource.

2. In the Database Options dialog box, choose a convenient ODBC Datasource.

3. When the AppWizard is finished, look at the DoFieldExchange function in the
  class derived from CRecordset. Notice that the order of the fields is the
  same as the table order.

4. Choose ClassWizard from the View menu to create a new Class derived from
  CRecordset.

5. In the Database Options dialog box, clear Bind all columns. Use the same ODBC
  Datasource as you did in step 2.

6. In the Member Variables tab of ClassWizard, click Bind all.

7. Look at the DoFieldExchange function for the newly created class. Notice that
  the fields are in alphabetical order.

Depending on the field types in the table and the SQL Statement used, this may
cause errors as listed above.

Additional query words:

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Keywords          : kberrmsg kbwizard kbDatabase kbMFC kbODBC kbVC500 kbVC600 kbGrpDSTools 
Technology        : kbVCsearch kbAudDeveloper kbClassWizard
Version           : WINNT:5.0, 6.0
Issue type        : kbprb
Solution Type     : kbpending

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