如何交換記錄值？

Question

如何使用role = 1將所有記錄更新爲值2並將role = 2記錄爲值1？

login | role 
----------+------ 
john  | 1 
anne  | 2 
adam  | 1 
robert | 1 
katie | 1 
bob  | 2 
tom  | 2 
...many records with 1 and 2 values 

Answer 1

UPDATE table 

SET role = CASE role 
       WHEN 1 THEN 2 
       ELSE 1 
      END 

WHERE role = 1 OR role = 2; 

Answer 2

UPDATE [table] 
SET role = CASE role 
       WHEN 1 THEN 2 
       ELSE 1 
      END 
WHERE role = 1 OR role = 2;