UPDATE dbo.TestStudents
SET LASTNAME =
( CASE
WHEN (LASTNAME = 'AAA') THEN 'BBB'
WHEN (LASTNAME = 'CCC') THEN 'DDD'
WHEN (LASTNAME = 'EEE') THEN 'FFF'
ELSE (LASTNAME)
END )
The statement work for the purpose but the else condition scan through every record in the table. Is there any way I can leave the unaffected rows as they are?
Add a WHERE
clause
UPDATE dbo.TestStudents
SET LASTNAME = CASE
WHEN LASTNAME = 'AAA' THEN 'BBB'
WHEN LASTNAME = 'CCC' THEN 'DDD'
WHEN LASTNAME = 'EEE' THEN 'FFF'
ELSE LASTNAME
END
WHERE LASTNAME IN ('AAA', 'CCC', 'EEE')