SELECT  
         stok_id
        ,  (SELECT MIN(miktar) FROM devir  WHERE stok_id=trz.stok_id) AS devir
        , (SELECT MIN(miktar) FROM hareket WHERE stok_id=trz.stok_id) AS hareket
FROM (
     SELECT stok_id FROM devir 
         UNION
     SELECT stok_id FROM hareket) AS trz

SELECT
  tmp.stok_id,
  d.miktar AS [devir],
  h.miktar AS [hareket]
FROM
  (
    SELECT stok_id FROM devir
    UNION
    SELECT stok_id FROM hareket
  ) AS tmp
LEFT JOIN devir d   ON (tmp.stok_id = d.stok_id)
LEFT JOIN hareket h ON (tmp.stok_id = h.stok_id)