UPDATE tcs
SET tcs.C_BELEPESDATUM = '20180901'
FROM T_TANULOCSOPORT tcs
  INNER JOIN T_TANEV te ON te.ID = tcs.C_TANEVID
  INNER JOIN T_INTEZMENY i ON i.ID = te.C_INTEZMENYID
WHERE te.C_NEV = '2018/2019'
  AND te.TOROLT = 'F'
  AND i.TOROLT = 'F'
  AND tcs.TOROLT = 'F'
  AND tcs.C_BELEPESDATUM = '20180903'