We use SUBD
PostgreSQL - free object-relational database management system (SUBD).
Exists in implementations for many UNIX-like platforms, including AIX, various BSD systems, HP-UX, IRIX, Linux, Mac OS X, Solaris/OpenSolaris, Tru64, QNX, and also for Microsoft Windows.
MySQL - a free relational database management system. MySQL is developed and supported by Oracle Corporation, acquired the trademark rights together with the acquired Sun Microsystems, which previously acquired the Swedish company MySQL AB. The product is distributed under the GNU General Public License, and under its own commercial license. Besides, developers create functionality ordered by licensed users, it is thanks to this order that the replication mechanism appeared in almost the earliest versions.
Firebird (FirebirdSQL) - compact, cross-platform, free database management system (SUBD), running on Linux, Microsoft Windows and various Unix platforms.
The advantages of Firebird include a multi-version architecture., providing parallel processing of operational and analytical queries (this is possible because, that reading users don't block writers), compactness (distribution kit 5Mb), high performance and powerful language support for stored procedures and triggers.
Software development environments
Qt C++ – cross-platform software development tools in the C++ programming language. Allows you to run software written with its help on most modern operating systems by simply compiling the program for each OS without changing the source code. Includes all main classes, which may be required when developing application software, from elements of the graphical interface to classes for working with the network, databases and XML. Qt is fully object oriented, easily extensible and supports component programming techniques.
Microsoft Visual Studio - Microsoft product line, including an integrated software development environment and a number of other tools. These products allow you to develop as console applications, and GUI applications, including with support for Windows Forms technology, as well as websites, web applications, native web services, and in managed code for all platforms, supported by Microsoft Windows, Windows Mobile, Windows CE, .NET Framework, Xbox, Windows Phone .NET Compact Framework и Microsoft Silverlight.