mysql - 带有选择/插入的奇数 CONCAT 错误

Question

这将返回行的任何原因：

select users.user_fullname,concat(persons.first_name,' ',persons.last_name)
from users, persons
where users.user_id = persons.user_id
and users.user_fullname = '0'

然而这会引发语法错误？

update users
set users.user_fullname = concat(persons.first_name,' ',persons.last_name)
from users, persons
where users.user_id = persons.user_id
and users.user_fullname = '0'

Answer 1

它与 . 无关CONCAT。问题是您不应该FROM在语句中包含子句UPDATE。

UPDATE users, persons
SET users.user_fullname = CONCAT(persons.first_name,' ',persons.last_name)
WHERE users.user_id = persons.user_id
AND users.user_fullname = '0'