PostgreSQL has Tcl/Tk interface library in the distribution called 'pgTcl'. Tcl/Tk is a Rapid Application Development tool and is a scripting language. You can develop once and run it everywhere on NT, Win 95, Linux, OS/2 and all unixes. Tcl stands for 'Tool Command Language' and Tk is 'Tool Kit'. There is a IDE (integrated development environment) for Tcl/Tk called SpecTcl. Check for this rpm package under Redhat linux distribution or at the sunscript site given below.
Perl is strongly recommended as a scripting language, since it is the most widely used and very powerful and is available on every hardware and OS platforms. Perl-Tk or Perl-Qt or C++ QtEZ or C++ Lesstiff is strongly recommended. A combination of Perl, C and Tk will satisfy the needs of most projects from viewpoint of time resources, speed of executable and ease of programming. Note that Java programs run very slow. Even C++ programs run slower than C programs. The C programs run the fastest as compared to other languages. Perl programs can be converted to "C" program using Perl2C program and than compiled which will be very fast.
Perl is used for programming 90 % of internet scripts in the world. So you will have only one language "Perl" for all your needs - in applications as well as internet. See Perl Database Interface of this document at Perl Database Interface
You should ponder over the strong points of Perl vis-a-vis Tcl/Tk before starting any project on Tcl. Tcl/TK is usually shipped with every linux cdrom. Also you can get it from these sites -