Can you check the below code, you can only update which are in Lower case.

DECLARE @tblName TABLE

(

NAME VARCHAR(100),

Action CHAR(1)

)

INSERT INTO @tblName

SELECT '090909f','N'

UNION ALL

SELECT '090909F','N'

Update @tblName SET name = UPPER(name),Action = 'U' where name COLLATE SQL_Latin1_General_CP1_CS_AS = Lower(name)

select * from @tblName where Action = 'U'