How to drop all tables in a MySQL database

... without destroying the database.

You can do it all in the shell:

Create a SQL script from the database to drop all the tables
Execute the SQL script against the database

mysql -u[pwd] -p[user] [dbname] -s -e 'show tables' | sed -e 's/^/drop table /' -e 's/$/;/' > dropalltables.sql
mysql -u[pwd] -p[user] [dbname] < dropalltables.sql