Select column from current table to a related table
Let’s join on player_id
SELECT * 
  FROM teams t INNER JOIN players p ON t.player_id = p.id
 WHERE t.created_at &gt;= DATE_SUB(CURDATE(), INTERVAL 30 DAY)
   and p.email = 'barcelonafc@outlook.com'

Be sure to verify if the results should be filtered on players added within the last 30 days or teams.