ALTER TABLE market_transactions ADD FOREIGN KEY (seller_id) REFERENCES
 accounts (id) ON DELETE SET NULL ON UPDATE CASCADE;
[b]Fehlermeldung:[/b]ERROR 1452 (23000):
 Cannot add or update a child row: a foreign key constraint 
fails (`d00e434e/#sql-13d9_4309ea`, CONSTRAINT `#sql-13d9_4309ea_ibfk_1`
 FOREIGN KEY (`seller_id`) REFERENCES `accounts` (`id`) ON DELETE SET NULL ON UPDATE CASCADE)