sts

UPDATE `table` SET `uid` = CASE
    WHEN id = 1 THEN 2 
    WHEN id = 3 THEN 4
    WHEN id = 5 THEN 6
    ELSE uid
    END
WHERE id  in (1,2,3)

UPDATE main m 
INNER JOIN test t ON (m.email1 = t.email AND m.email2 = t.email)
SET m.flag = 1