DataFlex 19.1 (and older) and the SQL drivers 6.3 (and older) only supported ANSI or OEM data. ANSI and OEM are single-byte encodings that are limited to 256 characters (no Unicode).
When using the full Unicode capabilities of DataFlex 20.0, only ANSI and Unicode character formats are supported. The OEM character format is still supported for backward compatibility and using the embedded database, but it is strongly recommended to migrate OEM tables to ANSI/Unicode.
With DataFlex 19.1/SQL drivers 6.3 (Oldgen), data can be stored as either ANSI or OEM in the database. This is specified by the Table_Character_Format setting in the table INT file.
ANSI and OEM code pages consist of 256 characters. The first 128 characters are the same for ANSI and OEM code pages (ASCII characters). The last 128 characters are different for ANSI and OEM codepages - these are called extended characters and contain the accented characters, amongst others.
Most database systems can store data as ANSI or OEM. This usually depends on code page settings of the SQL database, but ANSI code pages are the most common in SQL databases:
Normally, when the SQL database uses an ANSI codepage, the Table_Character_Format will also be set to ANSI, but it is also possible to use an ANSI code page for the database and have the Table_Character_Format set to OEM. Such tables we call OEM tables.
In Oldgen DataFlex the default settings in the drivers and DataFlex Studio were such that new tables would be created with Table_Character_Format set to OEM, even when the SQL database uses an ANSI code page. As a consequence, some DataFlex Oldgen systems have their tables defined as OEM tables where they really should have been ANSI.
Having OEM tables in an ANSI database means:
For instance, if the SalesPerson table is OEM, and accented characters are saved via Database Explorer, like pictured below:
In SQL Server Management Studio that same row will show as the following:
DataFlex 20.0/SQL drivers 20.0 now handle Unicode data. String data in databases can have various formats, including Unicode formats like UTF-8 or UTF-16. ANSI tables created with earlier (pre-20) DataFlex versions are supported and can be used in DataFlex 20 without changes. OEM tables are still supported in DataFlex 20, although this is just for backward compatibility. In general, OEM tables should no longer be used with DataFlex 20. Existing OEM tables should be converted to ANSI/Unicode. The Table_Character_Format setting in the table INT file is still used, but has a slightly expanded meaning.
This has now become a backward compatibility setting for OEM tables created with Oldgen drivers. With this setting, data is stored/retrieved to/from the database as OEM data.
Characteristics of OEM tables in Nextgen:
In DataFlex 20, OEM tables are only supported for backward compatibility. When migrating to DataFlex 20, OEM tables should be converted to ANSI/Unicode tables.
Database Builder in DataFlex 20 contains an OEM to ANSI Conversion Wizard to convert OEM tables to ANSI tables. The wizard will detect all OEM tables in a workspace that subsequently can be selected to convert to ANSI.
The OEM/ANSI conversion wizard will irreversibly change your data. Make sure you have proper backup of your entire database and all your INT files before running the conversion!
What's New in DataFlex 2021