UPDATE TA
SET TA.Trust_Desc = TB.Trust_Desc
FROM TB
INNER JOIN TA
ON TA.TrustID = TB.TrustID
AND TA.Trust_Desc like ''

UPDATE TA
SET TA.Trust_Desc = TB.Trust_Desc
FROM TB
INNER JOIN TA
ON TA.TrustID = TB.TrustID
AND TA.Trust_Desc = ''

AND TA.Trust_Desc like ''

AND TA.Trust_Desc = ''

UPDATE TA
   SET TA.Trust_Desc = TB.Trust_Desc
  FROM TB
 INNER JOIN TA
    ON TA.TrustID = TB.TrustID
   AND TA.Trust_Desc  = ''
   AND TB.Trust_Desc <> ''