Mine

SELECT m1.avizate, m2.facturate, m3.retururi, m1.monthFROM (SELECT count( 1 ) AS avizate, month( date_sent )MONTHFROM ordersGROUP BY month( date_sent ))m1, (SELECT count( 1 ) AS facturate, month( date_purchased )MONTHFROM ordersGROUP BY month( date_purchased ))m2, (SELECT count( 1 ) AS retururi, month(date_return )MONTHFROM ordersGROUP BY month( date_return ))m3WHERE m1.month = m2.month