sql 复制 插入列

来源：百度知道 编辑：UC知道 时间：2024/05/16 18:18:43
我有2个表，supe_spacenews，supe_spaceitems
其中关联的字段是itemid

我要把supe_spaceitems表中的subject这一列复制到表supe_spacenews中，
并且需要2个表中的itemid值对应

SQL语法是怎么样的？
2楼里面的 as a （
as b
这个 a、 b 是什么意思？怎么填写？
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这个2个表各有很多列，我只需要把supe_spaceitems表中的subject这一列复制到表supe_spacenews中，
并且需要2个表中的itemid值对应 。
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已经新建了subject列。

UPDATE supe_spacenews SET subject=(SELECT subject FROM supe_spaceitems where supe_spacenews.itemid=supe_spaceitems.itemid)

select subject into supe_spacenews from supe_spaceitems where supe_spaceitems.itemid =supe_spacenews.itemid

你要在supe_spacenews表中先键一个subject字段

insert into supe_spacenews as a (subject) select subject from supe_spaceitems as b where a.itemid =b.itemid

a 和 b 是这个表的别名,你也可以这样写

insert into supe_spacenews (subject) select subject from supe_spaceitems where supe_spacenews.itemid =supe_spaceitems.itemid

select subject into supe_spacenews from supe_spaceitems where supe_spaceitems.itemid =supe_spacenews.itemid

supe_spacenews表有没有subject这一列？没有的话，需要先创建，假设subject列的类型是varchar(100),语句如下
alter table supe_spacenews
add subject varchar(100)

然后，更新supe_spacenews表就可以了
update supe_spacenews
from supe_spaceitems
where supe_spaceitems.itemid=supe_spacenews.itemid