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Microsoft KB Archive/105540

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Knowledge Base


Article ID: 105540

Article Last Modified on 10/28/2003



APPLIES TO

  • Microsoft Visual Basic 3.0 Professional Edition
  • Microsoft Visual Basic 3.0 Professional Edition



This article was previously published under Q105540

SYMPTOMS

Trying to reference the properties of a Recordset or Database using a data control that was passed as Control to a Sub or Function results in this error message:

Invalid object reference

In addition, passing a data control into a Sub procedure as Control may result in a general protection (GP) fault, as it does in this example:

   Sub subtest (crtname As Control)
      crtname.UpdateControls
      ' Simply having this line in the code causes the GP fault.
      ' If you turn the line into a comment, the GP fault does not occur.
   End Sub
                

CAUSE

Recordset and Database specific properties are not available to objects passed as Control. You should replace the "As Control" with "As Data." NOTE: the Data object type is not easy to find in the Visual Basic documentation. It is, however, listed with the other possible object data types in the "Object Variables" popup on the Help menu topic, "Database Objects." Object types include CheckBox, ComboBox, CommandButton, CommonDialog, Control, Data, DirListBox, DriveListBox, FileListBox, Form, Frame, Grid, HScrollBar, Image, Label, ListBox, MDIForm, OptionButton, PictureBox, TextBox, Timer, and VScrollBar. The Professional Edition adds the following additional object types: Database, Dynaset, Field, Fields, Index, Indexes, QueryDef, Snapshot, Table, TableDef, and TableDefs.

WORKAROUND

Pass the data control as Data. For example, use the following code instead of the code shown below in the MORE INFORMATION section:

   Sub MySub(d As Data)
      Debug.Print d.Recordset.EOF
                

MORE INFORMATION

The following code example gives the error message:

   Sub MySub(d As Control)
      Debug.Print d.Recordset.EOF    ' an error appears on this line
                             '^^^      with EOF highlighted
                


Additional query words: 3.00 gpf

Keywords: kbprb KB105540