# вещи на которых можно навариться
SELECT * FROM `item_template` WHERE (`sellprice` * `buycount` > `buyprice`) and entry in (select item from npc_vendor);
SELECT * FROM `item_template` WHERE (`buycount` = 0) AND (`sellprice` > `buyprice`) and entry in (select item from npc_vendor);

#лишние записи по игрокам (все "SELECT *" можно смело менять на "DELETE" )
SELECT * FROM `character_action` where guid not in (select guid from `character`);
SELECT * FROM `character_aura` where guid not in (select guid from `character`);
SELECT * FROM `character_homebind` where guid not in (select guid from `character`); 
SELECT * FROM `character_inventory` where guid not in (select guid from `character`);
SELECT * FROM `character_kill` where guid not in (select guid from `character`); 
SELECT * FROM `character_pet` where guid not in (select guid from `character`); 
SELECT * FROM `character_queststatus` where guid not in (select guid from `character`);
SELECT * FROM `character_reputation` where guid not in (select guid from `character`); 
SELECT * FROM `character_social` where guid not in (select guid from `character`); 
SELECT * FROM `character_spell` where guid not in (select guid from `character`);
SELECT * FROM `character_spell_cooldown` where guid not in (select guid from `character`); 
SELECT * FROM `character_stable` where guid not in (select guid from `character`); 
SELECT * FROM `character_ticket` where guid not in (select guid from `character`);
SELECT * FROM `character_tutorial` where guid not in (select guid from `character`); 
SELECT * FROM `corpse` where `player` not in (select guid from `character`);
SELECT * FROM `character_inventory` where item not in (SELECT guid FROM `item_instance`);
SELECT * FROM `item_instance` where guid not in (SELECT item FROM `character_inventory`);
SELECT * FROM `character_queststatus` where quest not in (select `entry` from `quest_template`);
SELECT * FROM `character_social` where `friend` not in (select guid from `character`); 

# неверные предметы у продавцов ("SELECT *" -> "DELETE" для очистки)
SELECT * FROM `mangos`.`npc_vendor` WHERE `item` not in (SELECT `entry` FROM `item_template`);

# предметы для продажи есть, однако NPC не может их продать (flag не содержит 4)
# фиксить: 
# или изменить флаг (если это действительно продавец),
# или удалить записи из npc_vendor (если не продавец)
SELECT * FROM `creature_template` WHERE (`entry` in (SELECT `entry` from `npc_vendor`)) AND (`npcflag` & 4 <> 4);

# несуществующие продавцы
SELECT * FROM `npc_vendor` WHERE `entry` not in (SELECT `entry` from `creature_template`);

# несуществующие тренеры
SELECT * FROM `npc_trainer` WHERE `entry` not in (SELECT `entry` from `creature_template`);

# простая проверка на квесты (вообще их куча как в ядре, так и в моей программе)
SELECT * FROM `mangos`.`quest_template` where minlevel>questlevel

# аукцион
SELECT * FROM `auctionhouse` where `auctioneerguid` not in (select guid from `character`);
SELECT * FROM `auctionhouse` where `itemowner` not in (select guid from `character`);

# мобы с маленькими / неверными жизнями / уровнями
SELECT * FROM `mangos`.`creature` where curhealth < 20;
SELECT * FROM `mangos`.`creature_template` where minhealth>maxhealth;
SELECT * FROM `mangos`.`creature_template` where (minhealth< 20 ) or (maxhealth<20);
SELECT * FROM `mangos`.`creature_template` where minlevel>maxlevel;
SELECT * FROM `mangos`.`creature_template` where (minlevel=0) or (maxlevel=0);

# несуществующие мобы
SELECT * FROM `creature` c where id not in (select entry from creature_template);

UPDATE `item_template` SET `sellprice` = (`buyprice` /`buycount`) WHERE (`sellprice` * `buycount` > `buyprice`) and entry in (select item from npc_vendor);
UPDATE `item_template` SET `sellprice` = `buyprice` WHERE (`buycount` = 0) AND (`sellprice` > `buyprice`) and entry in (select item from npc_vendor);