The Paradox product line includes the following versions supported by the Microsoft Jet IISAM driver for Paradox: Paradox 3.x, Paradox 4.x, and Paradox 5.x. Paradox databases differ from Microsoft Jet databases in three major areas: data types, handling of indexes and keys, and dependency on network resources. The following sections describe these differences.
Microsoft Jet translates each Paradox data type into the corresponding Microsoft Jet data type when your application reads the data. The following table shows the one-to-one correspondence between data types.
| Paradox data type* | Microsoft Jet data type |
| Alphanumeric | Text |
| Number | Double |
| Short number | Integer |
| Currency | Double |
| Date | Date/Time |
| Memo | Memo |
| OLE |
Long Binary (OLE Object) (Note that the Microsoft Jet database engine recognizes the object but will not let you open it.) |
| Logical (Paradox 5.x) | Boolean |
| Integer (Paradox 5.x) | Long |
| Timestamp (Paradox 5.x) | Date/Time |
| Binary (Paradox 5.x) | Binary |
| BCD (Paradox 5.x) | Double |
| Time (Paradox 5.x) | Date/Time |
| Autoinc (Paradox 5.x) | AutoNumber |
| * Paradox Graphic, Binary, and Formatted memo types aren’t supported and won’t appear when you display external Paradox tables. |
Paradox uses a .px index file to store primary key information for each table that has a primary key. Microsoft Jet must be able to locate the .px index file each time you attempt to use the table. If the .px file is unavailable, Microsoft Jet will be unable to open the Paradox table.
You cannot update data in a Paradox table that has no primary key. Also, you cannot open, in shared mode, a Paradox table that has no primary key.
Microsoft Jet uses three settings to control user access to Paradox tables that reside on a file server. You can set each of these settings in the \HKEY_LOCAL_MACHINE
\SOFTWARE\Microsoft\Jet\3.5\Engines\Paradox key in the registry.
The first setting, ParadoxNetPath, indicates the location of the network control file Paradox.net (for Paradox 3.x databases) or the file Pdoxusrs.net (for Paradox 4.x and 5.x databases). This setting must be identical for all users who are accessing a particular Paradox database.
The second setting, ParadoxUserName, is a string value that is displayed in Paradox to an interactive Paradox user when the user attempts to place a lock that is incompatible with the lock held by the Microsoft Jet Paradox IISAM driver.
The third setting, ParadoxNetStyle, indicates whether users are accessing the Paradox database using the Paradox 3.x or Paradox 4.x locking method.
For more information about Paradox network dependencies and locking methods, see the documentation for Paradox.
See Also For more information about Paradox-specific settings in the registry, see the Paradox section of Appendix C, “Registry Settings.”