MySQL相关子查询

Question

任何人都可以帮我解决相关嵌套子查询的问题 即，当我试图在嵌套的子查询中使用祖父列时，我得到了这个错误

错误代码：1054 'where子句'中的未知列'scu.iUserId'

查询：

    SELECT 
      scu.iUserId,
      (SELECT 
        SUM(
          sbs.`iNoPointsBeginning` + 
          (SELECT 
            COALESCE(SUM(BehaviorPts), 0) AS StudentPts 
          FROM
            (SELECT 
              (
                COUNT(sbis.iIncidentSubmissionId) * sbi.iPointValue
              ) AS BehaviorPts 
            FROM
              scn_behavior_incident_submission sbis 
              JOIN scn_behavior_incident_actors sbia 
                ON sbia.iIncidentSubmissionId = sbis.iIncidentSubmissionId 
              LEFT JOIN scn_behavior_incidents sbi 
                ON sbi.iIncidentId = sbis.iBehaviorIncidentId 
            WHERE sbia.iUserId = scu.iUserId
              AND sbia.eActorType  'Witness' 
              AND sbis.iSchoolId = '875' 
            GROUP BY sbis.iBehaviorIncidentId) AS BehaviorTotal)
        ) AS stu_pt 
      FROM
        scn_behavior_settings sbs 
      WHERE sbs.`iSchoolId` = '875') 

    FROM
      scn_sections_members AS scm 
      INNER JOIN scn_users AS scu 
        ON scu.iUserId = scm.iStudentId 

Answer 1

两个嵌套级别会导致此错误。内部子查询不“知道”在外部查询中定义的scu。

尝试在没有内联子查询的情况下重写它。不确定这是否是正确的方法，但你会明白。 （sbs表似乎与其他表无关，因此我将其设为CROSS JOIN。如果存在关系则适当编辑）：

SELECT 
    scu.iUserId,
    sbs.iNoPointsBeginning 
    + COUNT(sbis.iIncidentSubmissionId) * COALESCE(sbi.iPointValue, 0)
      AS stu_pt 
FROM
    ( SELECT 
          SUM(sbs.iNoPointsBeginning) AS iNoPointsBeginning
      FROM 
          scn_behavior_settings sbs 
      WHERE sbs.iSchoolId = '97'
    ) AS sbs 
  CROSS JOIN
      scn_sections_members AS scm 
  INNER JOIN scn_users AS scu 
    ON scu.iUserId = scm.iStudentId 
  LEFT JOIN
          scn_behavior_incident_submission sbis 
        JOIN scn_behavior_incident_actors sbia 
          ON  sbia.iIncidentSubmissionId = sbis.iIncidentSubmissionId 
          AND sbia.eActorType = 'Witness' 
          AND sbis.iSchoolId = '97' 
        LEFT JOIN scn_behavior_incidents sbi 
          ON sbi.iIncidentId = sbis.iBehaviorIncidentId 
    ON sbia.iUserId = scu.iUserId
GROUP BY scu.iUserId
       , sbis.iBehaviorIncidentId

Answer 2

如果你（暂时）删除那些混乱的子查询，你会看到你在说：

SELECT scu.iUserId 
FROM scn_sections_members AS scm 
INNER JOIN scn_users AS scu 
ON scu.iUserId = scm.iStudentId

要让MySQL告诉您该列未知，它必须表示该列不存在。 scn_users的定义是什么？在该表中放置一个iUserId列，然后至少那部分问题将结束。