If he does that, he will overwrite every table...
Export everything just in case, then manually execute the sqls:
accounts, character_friends, castle_functions, character_hennas, character, macroses, character_quest_global_data, character_quests, character_recipebook, character_shortcuts, character_skills, character_subclasses, characters, clan_data, clan_notices, clan_privs, clan_skills, clan_subpledges, clan_wars, clanhall, clanhall_functions, fort, fort_functions, item_attributes, items
This way you will keep: accounts, castles, forts, everything char and clan related