Export Table - DBF

DBF refers to a family of formats originally used with the dBase database management system. The format is now used with Microsoft's FoxPro DBMS as well as in many Windows and UNIX / Linux DBMS applications that can save database tables. Unfortunately, there is no universal standard for what constitutes a ".dbf" file. The original dBase format limits field names to eight alphanumeric characters not beginning with a number. It also limits file names to eight alphanumeric characters plus a three-letter extension. More recent ".dbf" drivers will allow nine or eleven character filenames and field names. Some UNIX drivers may impose no limitation on file or field names.

 

To export a table to .dbf format:

 

1. Open the table in a table window.

2. Choose File - Export - Table from the main menu.

3. In the Export dialog choose DBF Files in the Save as type box and specify a filename to use. Press Save.

4. Check the fields that are to be exported. Buttons provide for Select All, Select None and Select Inverse to rapidly change which fields are to be exported for tables containing many fields.

5. Check use dBase format for greatest compatibility with older databases; however, if this box is checked and field names or file names are longer than 8 simple alphanumeric characters the export will not succeed.

 

Controls

 

Subtype

Choose dBase or FoxPro .dbf format for compatibility with older applications.

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Select All - Check all fields. All data fields in the table will be exported.

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Select None - Uncheck all fields. No data fields will be exported. Tech tip: Use this to uncheck all fields before checking those desired.

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Select Inverse - Uncheck all previously checked fields and check all previously unchecked fields. This is a fast way to check only a few columns out of many: uncheck those desired and then push Select Inverse.

Fields pane

Check the fields to be exported.

 

One problem with .dbf formats is that the specific nature of what is allowed or disallowed in the format varies greatly depending on the drivers or applications that are used. In particular, some applications can use longer names for files and fields than can other applications using a ".dbf" format. Manifold will use whatever .dbf drivers are available on the host Windows system, by default installing the FoxPro and .dBase .dbf Microsoft drivers.

 

For maximum compatibility it is best to use filenames and fieldnames that are eight characters or fewer in length. Use only letters and numbers in the name and do not start a filename or field name with a number. Do not use any special characters such as spaces, parentheses or underscores. Most modern drivers will allow 11 character filenames and field names, as do the default .dbf drivers installed with Manifold. However, it is wise to truncate file and field names to only 8 characters if you plan on exchanging data with other ".dbf" capable applications.

 

Because of the wide variation in drivers and field and file naming conventions in common use, .dbf is not a good choice for reliable data interchange unless it is limited to the least common denominator of using very restricted field and file names. However, such a primitive approach to naming is very costly because it denies us the ability to use descriptive field and file names that are self-documenting.

 

A better choice for data interchange in the Microsoft world is to export to Microsoft's .mdb format whenever possible.

 

Internationalization

 

Exporting a .dbf file (either by exporting a table as a .dbf or by exporting a drawing as a shapefile) will set the .dbf codepage field to the codepage used by the columns in the exported table. If the columns use conflicting codepages or if the codepage is not supported by .dbf format, Manifold will display a warning message.

 

Importing a .dbf file (either by importing a table from a .dbf or by importing a drawing from a shapefile) sets the codepage of each text column to that used in the .dbf file.