Question

update moodlesocialuser 
set moodlesocialuser.deleted=deleted+1 
where id IN (
  select m1.id 
  from moodlesocialuser m1 
  join moodlesocialpost m2 on m1.id=m2.userid 
  where m2.module='blog' 
  and m1.deleted='0' 
  and url like 'http%' 
  and m1.id NOT IN (
    select id from moodlesocialcourse_display
  ) 
);

我无法进行更新并从同一张表中选择。

错误1093（HY000）：您无法在FROM子句中指定目标表'moodlesocialuser'以进行更新。

我该怎么做？

Answer 1

如果此查询中没有聚合函数，为什么使用group by子句？注释掉group by子句和脚本将运行没有任何错误。

Answer 2

看起来您在该UPDATE语句中复制粘贴现有查询。您可以在第一个子查询中删除m1别名，如下所示：

update moodlesocialuser 
set moodlesocialuser.deleted=deleted+1 
where id IN (
  select m2.userid
  where m2.module='blog' 
  and url like 'http%'
)
and moodlesocialuser.deleted='0' 
and id NOT IN (
    select id from moodlesocialcourse_display
)

Answer 3

错误消息显示，您正在尝试更新您正在阅读的表格。

使用临时表：

create temporary table foo (id int);

insert into foo 
  select m1.id 
  from moodlesocialuser m1 
  join moodlesocialpost m2 on m1.id=m2.userid 
  where m2.module='blog' 
  and m1.deleted='0' 
  and url like 'http%' 
  and m1.id NOT IN (
    select id from moodlesocialcourse_display
  ) 
;

update moodlesocialuser m
inner join foo on m.id = foo.id
set m.deleted=deleted+1 
;

drop table foo;

Answer 4

您无法修改从(read more here)中选择的表格;另一方面，我认为你可以摆脱那个子查询，就像这样（我不认为下面的查询会真正起作用，你最好在非有价值的数据上测试它;我想说的是 - 你是也可以加入更新）：

UPDATE moodlesocialuser mu, moodlesocialcourse_display md, moodlesocialpost mp
SET mu.deleted=mu.deleted + 1 
WHERE
md.id != mu.id AND
mu.deleted = 0 AND
mp.userid = mu.id AND
mp.module = 'blog' AND
mp.url LIKE 'http%'

如何修复选择并更新到同一个表

4 个答案: