DataFlex Support

DataFlex Support
Indexes

FLEX/ODBC uses the ORDER BY clause in SQL and attempts to match the first fields (columns) of the ORDER BY to an existing index. If a match is found, that index is used for the sort order. If no match is found, the data is retrieved by the driver and sorted with a sort engine in memory.

If the ORDER BY clause and the WHERE clause use the same field names, the system will "jump-in" to the index to find records, and "jump-out" when the set is complete, increasing performance.

Dates

Dates in FLEX/ODBC are returned in the SQL standard date format of 'YYYY-MM-DD'. This format allows proper sorting from all environments.

In the control panel there is a setting for the number of digits to use for the years of dates. You should set this to match your system and tell the driver if you use 4 or 2 digit year format. This will affect correct operation of comparisons of date values.

DFPATH

The driver allows multiple FILELIST.CFG files to be used on a system by defining multiple data source entries, and giving each the directory path where the files can be found.

If you prefer, this entry can be left as "." and if the DOS environment variable DFPATH is set, it will use this path for finding files.

Pathnames embedded in the FILELIST.CFG are respected to allow files to be accessed in multiple directories from a single filelist.

Record Number

You can choose whether or not you wish the DataFlex Record Number to appear in queries as the first field. The default operation is to show this field. This can be changed in the Control Panel.

Note: Some applications cannot change data in an ODBC file without a primary index key. Record Number is used for this purpose in FLEX/ODBC, so changing this setting may disallow updates in certain applications, most notably Microsoft Access.

Read-Only Operation

FLEX/ODBC can be configured to not allow users to update data in DataFlex files. For casual use you can set the read-only flag in the Control Panel. If this is not protection enough, you can click on the "Make FLEX/ODBC Read-Only" icon which is installed by the driver. This will make the driver unable to write to DataFlex files, and this cannot be reversed without re-installing the driver.

Header Integrity Checking

The 16 bit version of this product currently does not support writing to DataFlex files where Header Integrity Checking has been enabled. They can be read however. The 32 bit version does not have this limitation.