子组外的引用字段（where 子句中的未知列）

Question

我试图在子查询中引用 a.pointer，但看起来 mysql 不允许引用子查询外的字段。

UPDATE order_items AS a

SET a.id_parent = (

SELECT id FROM((

select id from order_items as b where (b.pointer = a.pointer) and (b.id_parent = 0)) 

)x) 

WHERE a.id_parent > 9999

在子查询中访问 a.pointer 的最佳方法是什么？

Answer 1

尝试为此使用连接

UPDATE order_items as a
SET a.id_parent = b.id    
JOIN(select id from order_items as c where  c.id_parent = 0) b ON b.pointer = a.pointer
WHERE a.id_parent > 9999

Answer 2

您似乎想在这里进行自连接；像

UPDATE order_items a 
    JOIN order_items b ON b.pointer = a.pointer AND b.id_parent = 0
SET a.id_parent = b.id
WHERE a.id_parent > 9999;

Answer 3

UPDATE  a
SET a.id_parent = b.id
from order_items a join order_items b 
on (a.pointer = b.pointer )
where b.id_parent = 0 and a.id_parent > 9999

您可以像上面那样使用自连接。

谢谢

子组外的引用字段（where 子句中的未知列）

Reference field outside the subgroup (Unknown column in where clause)

mysql

sql

database

subquery