How to set default database

Hello!

I created database "krzysztof" for practice postgresql. After few days i
  deleted that database and i created the next one "cwiczebna". Now when
I type "psql" i get strange info, something like: "CRITICAL: base
"krzysztof" don't exist". Now i need to  type "psql cwiczebna" to log in
to new database. How to set the default database or connect
automatically to "cwiczebna" database when I type "psql" in terminal. I
am using Debian Lenny distro.
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Krzysztof Walkiewicz
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bars0@op.pl