This is a maintenance release of Rel, an implementation of Date & Darwen’s Tutorial D database language. The most significant new feature is the ability to connect to external CSV files, XLS and XLSX spreadsheets, Microsoft Access databases, and JDBC database connections, and represent their contents as relation-valued variables (aka relvars). Facilities have also been provided to easily export relvars and query results as CSV and spreadsheet (XLS or XLSX) files.
IMPORTANT NOTE: Once opened with this or later versions of Rel, databases cannot be read by earlier versions.
The following enhancements have been made:
- Support for UNORDER() (the inverse of ORDER(), to convert an ARRAY to a RELATION) has been added to the visual query editor in the Rel user interface.
- In the Rel user interface, a “refresh” toolbar item has been added to VIEWs, the same as for VARiables.
- In the Rel user interface, the visual query editor’s “View Query” ‘?’ dialog now provides option to emit query text, or VIEW and OPERATOR definitions, directly to command-line. Furthermore, the dialog box is no longer modal; makes it easier to use query definition elsewhere.
- In the Rel user interface’s command-line, the initial use of the Save dialog defaults to directory of the most recent Load, if Load used first. Likewise, the initial Load dialog defaults to directory of most recent Save, if Save is used first.
- In the Rel user interface, Variables (relvars), Views, and visual query results may now be exported to CSV text files and XLS/XLSX spreadsheet files.
- In the standalone Rel DBMS, all application .jars have been moved to the /lib subdirectory.
- Support for accessing CSV files, XLS/XLSX spreadsheet files, Microsoft Access databases, and JDBC databases for various popular DBMSs, and representing their contents as relation-valued variables (relvars) is now built-in. See https://reldb.org/c/index.php/read/accessing-external-data-sources/ for further information.
The following bugs have been fixed:
- In the Rel user interface, spaces in application path caused external Java-based operator compilation to fail. Fixed.
- In the Rel user interface, the “Get File Path” button now correctly returns backslashes in file path as ‘\\’.
- In the Rel user interface, failing to open a database could allow all database tabs to be closed, which left the Rel UI in an unstable state. Fixed.
For more information, or to download Rel, go to https://reldb.org