Xojo, formerly known as REALBasic, is an integrated set of advanced tools including a programming language, a sophisticated visual drag-and-drop GUI layout editor, and multi-platform compilers. Think of Xojo as Visual Basic reborn and vastly improved.
Xojo is easy enough for a beginner to learn programming but also powerful enough for daily use by professional developers. The language is fully object-oriented and uses modern compiler technology. Comes with thorough documentation, both reference and tutorial.
The development tools run on several Linux distros, Microsoft Windows and macOS.
Desktop apps deploy to those 3 platforms (Linux/Win/Mac) as well as deploying to Raspberry Pi. See the System Requirements page for details.
You can also build iOS apps, but only when running Xojo on macOS with access to Xcode.
Xojo supports a variety of databases, including: SQLite, PostgreSQL, MySQL, Microsoft SQL Server and Oracle. See the page, Xojo and databases.
By the way, here is a fresh article about Xojo 2016 Release 3 shipping.
The Xojo Developer Conference (XDC) is next month in Houston TX.