ISAMCVT Doesn't Properly Convert db/LIB Date Fields (69158)

SYMPTOMS

Pages 148-149 of the "Microsoft Visual Basic for MS-DOS: Professional Edition Features" manual states that the ISAMCVT utility will convert db/LIB date fields to Basic double-precision numbers for use with the Date/Time add-on libraries. This information is also listed on Page 393 of the "Microsoft Basic 7.0: Programmer's Guide" (for versions 7.0 and 7.1).

ISAMCVT does convert a date field to a double-precision number, but the resulting number is not a serial number that can be used with the date libraries included with Visual Basic for MS-DOS, or Basic PDS.

STATUS

Microsoft has confirmed this to be a bug in the ISAMCVT.EXE utility for the Professional Edition of Microsoft Visual Basic for MS-DOS, version 1.0, and for Microsoft Basic Professional Development System (PDS) for MS-DOS, versions 7.0 (buglist7.00) and 7.1 (buglist7.10). We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

When ISAMCVT converts a date field, it converts it to a 8-byte string, but tags it internally as a double. To see the string, you must use the MKD$ function to convert the double to a string.

However, ISAMCVT also converts the year portion of the date incorrectly by dropping the last two digits (for example, 1990 becomes 19, and 1890 becomes 18.)

For example, if you have a db/LIB file ("test.dbf") containing three fields and one record

NUMERIC (length=4, # decimals=1) = 1.2
CHARACTER (length = 50) = My Name
DATE = 19901214

and you convert it using the following command:

ISAMCVT /D test.dbf table test.mdb

The program listed below will then show that the ISAM file contains the following:

CustNum = 1.2
Name = My Name
Date = 12/14/19

Code Sample

NOTE: PROISAM.EXE must be loaded before running this program inside of VBDOS.EXE or QBX.EXE.

' To try this example in VBDOS.EXE:
' 1. From the File menu, choose New Project.
' 2. Copy the code example to the Code window.
' 3. Press F5 to run the program.
TYPE rectype
    CustNum AS DOUBLE
    Name AS STRING * 50
    Date AS DOUBLE
END TYPE
DIM a AS rectype
OPEN "test.mdb" FOR ISAM rectype "table" AS #1
SETINDEX #1, ""
MOVEFIRST #1
RETRIEVE #1, a
PRINT a.CustNum
PRINT a.Name
PRINT MKD$(a.Date)
CLOSE #1