I did that using the following query.
UPDATE SchemeMember
SET personID = b.personUID
FROM SchemeMember s,benefit b
WHERE s.Id = b.SchemeMemberId  
solved Update newly added column with value on another table
 
I did that using the following query.
UPDATE SchemeMember
SET personID = b.personUID
FROM SchemeMember s,benefit b
WHERE s.Id = b.SchemeMemberId  
solved Update newly added column with value on another table