getting table metadata

[Yves Glodt]

Hi,

is it possible to get information about tables by doing queries on some system 
tables? I am using mysql version 4.1.11 on debian sarge.

In my case I need to know which columns (names and types) a table has, and how 
the primary key is defined.

How can I get this information out of mysql by only using sql ?

Best regards,
Yves