相关疑难解决方法(0)

SELECT
      i.*, 
      r.name AS roomname, 
      c.name AS cat, 
      p.key AS imgkey, 
      p.extension AS imgext
   FROM 
      items i, 
      rooms r, 
      categories c 
         LEFT JOIN photos p 
            ON p.referencekey = i.key 
   WHERE 
          i.room = r.key 
      AND r.key = 663308 
      AND i.sitekey = 32201 
      AND c.key = i.categorykey

执行时上面的查询返回以下错误.

错误:对表"i"的FROM子句条目的无效引用

第1行:... tegory c LEFT JOIN photos p ON p.referencekey = i.key WHER ...

提示:表"i"有一个条目,但不能从查询的这一部分引用它.

为什么在组合外部和内部连接时表的顺序很重要？postgres失败如下:

SELECT grp.number AS number,     
       tags.value AS tag   
FROM groups grp,
     insrel archiverel  
LEFT OUTER JOIN ownrel ownrel ON grp.number = ownrel.dnumber   
LEFT OUTER JOIN tags tags ON tags.number = ownrel.snumber   
WHERE archiverel.snumber = 11128188 AND    
      archiverel.dnumber = grp.number 

结果:

ERROR:  invalid reference to FROM-clause entry for table "grp" LINE 5: LEFT OUTER JOIN ownrel ownrel ON grp.number = ownrel.d... 
^ HINT:  There is an entry for table "grp", but it cannot be referenced from this part of the query. …

我在查询中遇到以下错误：

here is an entry for table "table1", but it cannot be referenced from this part of the query.

这是我的查询：

SELECT id 
FROM property_import_image_results table1
  LEFT JOIN (
    SELECT created_at 
    FROM property_import_image_results
    WHERE external_url = table1.external_url
    ORDER BY created_at DESC NULLS LAST 
    LIMIT 1
  ) as table2 ON (pimr.created_at = table2.created_at)
WHERE table2.created_at is NULL