Drupal Dr.

To ignore some tables while backingup database use the following.. mysqldump -u dave -ppassword -h localhost --ignore-table=my_db_name.my_table_name my_db_name > dump.sql

Deleting forum from drupal, only delete terms, if you want to delete all its nodes, comments and terms from database, truncate the follwing tables from Drupal Database. truncate comments; truncate content_type_forum; truncate forum; truncate node; truncate node_revisions; truncate term_data; truncate term_hierarchy; truncate term_node; truncate users; truncate node_comment_statistics; Other Option if you want to drop all the tables at once to restore the new data drop table comments, content_type_forum, forum, node, node_revisions, term_data, term_hierarchy, term_node, users, node_comment_statistics;