Как сформировать sql запрос для выборки из двух таблиц?

SELECT * FROM `t1` WHERE `id` IN (SELECT `id_iz_pervoi_tablici` FROM `t2` WHERE `flag`=0)

SELECT * FROM `t1` WHERE EXISTS (SELECT * FROM `t2` WHERE `t1`.`id` = `t2`.`id_iz_pervoi_tablici` AND `flag`=0)

SELECT * FROM `t1` 
  LEFT JOIN (SELECT * FROM `t2` WHERE `flag`=0)  AS `t2`
  ON `t1`.`id` = `t2`. `id_iz_pervoi_tablici`

SELECT t1.*
  FROM t1
  JOIN t2 ON t2.id_iz_pervoi_tablici = t1.id
  WHERE t2.flag = 0