You can enable the query cache (available as of MySQL 4.0.1) by setting query_cache_type to an appropriate value in my.cnf:
query_cache_type = 1
As far as the cache is concerned, the query:
SELECT * FROM table1
is different from:
select * FROM table1
It is possible to tell MySQL that it should not cache a given query, however. The way to dodge the query cache is to add the SQL_NO_CACHE hint to your query.
SELECT SQL_NO_CACHE * FROM mytable
