The information in this article applies to:
- Microsoft Visual Basic Professional and Enterprise Editions for
Windows, version 5.0
- Microsoft Visual Basic Professional and Enterprise Editions, 32-bit
only, for Windows, version 4.0
- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0
- Microsoft Visual Basic for Applications (VBA) included with:
- Microsoft Access versions 7.0, 97
- Microsoft Excel, versions 7.0, 97 for Windows
- Microsoft Word 97 for Windows
- Microsoft PowerPoint 97 for Windows
SYMPTOMS
Trying to set a Visual FoxPro Date field to Null via DAO/ODBC results in
the following error:
"Run-time error '3162':
Null Is Invalid."
CAUSE
The FoxPro ODBC driver does not use Null for an empty date.
RESOLUTION
Set the date field to 12/30/1899 instead. The Visual FoxPro ODBC driver
translates this value into an empty date.
STATUS
This behavior is by design.
MORE INFORMATION
In Visual Basic and other VBA and DAO applications, dates are stored as the
number of days since 12/30/1899. This date is stored internally as the
number 0. The Visual FoxPro ODBC driver takes this 0 value to represent an
empty date.
Steps to Reproduce Behavior
- Create and execute the following Visual FoxPro program:
CREATE DATABASE ztest
CREATE TABLE ztest (dfield d)
APPEND BLANK
REPLACE dfield WITH {3/15/96}
USE
- In Visual FoxPro, modify the Database "ztest" and add the table "ztest"
to the database. Add an additional character field and create a Primary
Key (this is required for the ODBC driver to write back to the table).
Exit Visual FoxPro and create a Visual FoxPro data source called ztest,
which points to the database ZTEST.DBC.
- Create a new Visual Basic or VBA project. Make sure that Microsoft DAO
3.0 or 3.5 object library is included in your References.
- Add the following code to a Module:
Sub Test_VFP_Date()
Dim db As Database, rs As Recordset
Set db = OpenDatabase("", False, False, _
"ODBC;database=testdata;uid='',pwd=;dsn=ztest")
Set rs = db.OpenRecordset("ztest")
rs.Edit
rs!dfield = Null
rs.Update
End Sub
- Run the code from the Immediate Window. If prompted for ODBC connection
information, select the ztest data source. Then, select the ztest
table and click OK.
- You will receive the run-time error described above for the line:
rs!dfield = Null
- Change the line to either:
rs!dfield = #12/30/1899#
-or-
rs!dfield = 0
and rerun the application.
- Open the ztest table in Visual FoxPro to verify the date is now blank.
REFERENCES
For more information, please see the following article in the Microsoft
Knowledge Base:
ARTICLE-ID: Q150433
TITLE : PRB: 12/30/1899 Appears as a Blank Date in Microsoft Access
Keywords : APrgDataODBC vb432 VB4WIN vb5all VBKBDB VBKBJet vbwin GnrlVb kberrmsg kbprg
Technology : kbvba
Version : WINDOWS:3.0 4.0 5.0
Platform : WINDOWS
Issue type : kbprb