Tcl is a surprisingly simple language.
Having said that, I should point out that solving complex problems is not necessarily easier in Tcl than in other languages, you just have fewer syntactic rules to remember. Tcl is not a panacea, just a really nice little language.
The libpgtcl library fits into Tcl very nicely. If you want to toss together a PostgreSQL client application quickly, explore Tcl and libpgtcl.
Part I: General PostgreSQL Use
Introduction to PostgreSQL and SQL
Working with Data in PostgreSQL
PostgreSQL SQL Syntax and Use
Performance
Part II: Programming with PostgreSQL
Introduction to PostgreSQL Programming
Extending PostgreSQL
PL/pgSQL
The PostgreSQL C APIlibpq
A Simpler C APIlibpgeasy
The New PostgreSQL C++ APIlibpqxx
Embedding SQL Commands in C Programsecpg
Using PostgreSQL from an ODBC Client Application
Using PostgreSQL from a Java Client Application
Using PostgreSQL with Perl
Using PostgreSQL with PHP
Using PostgreSQL with Tcl and Tcl/Tk
Using PostgreSQL with Python
Npgsql: The .NET Data Provider
Other Useful Programming Tools
Part III: PostgreSQL Administration
Introduction to PostgreSQL Administration
PostgreSQL Administration
Internationalization and Localization
Security
Replicating PostgreSQL Data with Slony
Contributed Modules
Index