sql update set使用case when语句

示例一：

UPDATE `table` 
SET `djyzmdm` = NULL,
`djyzmsj` = NULL,
`dlcs` =
CASE WHEN 
        `dlcs` IS NULL THEN
        1 
        ELSE 
        `dlcs` + 1 
    END 
WHERE
    `id` = 1

示例二：

UPDATE `table` 
SET `datetime` = 1434567890,
`status` =
CASE
        `id` 
        WHEN 12 THEN
        1 
        WHEN 13 THEN
        2 
        WHEN 14 THEN
        3 
    END 
WHERE
    `id` IN (12,13,14)