UPDATE employee
SET staff_no =
CASE depno
WHEN 1 THEN 'ab123'
WHEN 2 THEN 'ab321'
--...
ELSE staff_no
END
WHERE depno IN ( 1, 2 ) -- list all cases here. use a subquery if you don't want to / cannot enumerate
UPDATE
table_name
SET
column1 = value1,
column2 = value2,
column3 = value3,
...
WHERE
condition;
Code language: SQL (Structured Query Language) (sql)