I want to use CASE statement to update some records in sql server 2005

Question

UPDATE dbo.TestStudents  
SET LASTNAME = 
( CASE  
WHEN (LASTNAME = \'AAA\') THEN \'BBB\' 
WHEN (LASTNAME = \'CCC\') THEN \'DDD\' 
WHEN (LASTNAME = \'EEE\') THEN \'F         


        

Answer 1

If you don't want to repeat the list twice (as per @J W's answer), then put the updates in a table variable and use a JOIN in the UPDATE:

declare @ToDo table (FromName varchar(10), ToName varchar(10))
insert into @ToDo(FromName,ToName) values
 ('AAA','BBB'),
 ('CCC','DDD'),
 ('EEE','FFF')

update ts set LastName = ToName
from dbo.TestStudents ts
       inner join
     @ToDo t
       on
         ts.LastName = t.FromName