PRB: ClassWizard Binds Fields in Incorrect Order Causing Errors

• The ClassWizard, included with:
  • Microsoft Visual C++, 32-bit Editions, versions 5.0, 6.0

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

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.

Additional query words:

Keywords : kberrmsg kbwizard kbDatabase kbMFC kbODBC kbVC500 kbVC600 kbGrpDSTools
Version : WINNT:5.0, 6.0
Platform : winnt
Issue type : kbprb