为什么这个列在ON子句中是未知的？(Why is this column unknown in ON clause?)

 我有以下声明： 
 
SELECT
  p1.order_id,
  p1.job_id,
  j1.`status` AS p1_status
FROM
  wildcard_orders AS p1,
  wildcard_orders AS p2
LEFT JOIN wildcard_jobs AS j1 ON p1.job_id = j1.id
LEFT JOIN wildcard_jobs AS j2 ON p2.job_id = j2.id 
WHERE
  p1.order_id = p2.order_id 
  AND p1.job_id != p2.job_id
 
 基本上，我试图获得在同一个表中具有不同job_id重复order_id 。 
 
 我把它缩小到在FROM子句中包含相同的表但我相信我之前已经这样做了！ 
 
 我得到的确切错误是： 
 
1054 - Unknown column 'p1.job_id' in 'on clause'
 
 谁能帮忙解决原因？ 

I have the following statement:
 
SELECT
  p1.order_id,
  p1.job_id,
  j1.`status` AS p1_status
FROM
  wildcard_orders AS p1,
  wildcard_orders AS p2
LEFT JOIN wildcard_jobs AS j1 ON p1.job_id = j1.id
LEFT JOIN wildcard_jobs AS j2 ON p2.job_id = j2.id 
WHERE
  p1.order_id = p2.order_id 
  AND p1.job_id != p2.job_id
 
Basically, I am trying to get duplicate order_id that have a different job_id in the same table.
 
I've narrowed it down to including the same table in the FROM clause but I am sure I have done this before!
 
The exact error I get back is:
 
1054 - Unknown column 'p1.job_id' in 'on clause'
 
Can anyone help with why?

原文：https://stackoverflow.com/questions/46459299