SELECT 
    `transaction`.*
FROM 
    `transaction` 
    LEFT JOIN `transaction_2` ON `transaction`.`id` = `transaction_2`.`transaction_id`
WHERE 
    transaction.deleted IS NULL 
    AND 
    (SELECT SUM(summ) FROM transaction_2 WHERE transaction_id = transaction.id) IS NULL 
    OR transaction.summ - (SELECT SUM(summ) FROM transaction_2 WHERE transaction_id = transaction.id) <> 0

SELECT
  transaction.id,
  transaction.summ,
  SUM(transaction_2.summ)
FROM transaction
LEFT JOIN transaction_2 ON transaction.id = transaction_2.transaction_id
WHERE transaction.deleted IS NULL
GROUP BY transaction.id
HAVING SUM(transaction_2.summ) IS NULL OR SUM(transaction_2.summ) <> transaction.summ