postgresql 返回表错误：列引用不明确答案

【问题标题】：postgresql return table ERROR: column reference is ambiguouspostgresql 返回表错误：列引用不明确
【发布时间】：2016-08-12 12:19:43
【问题描述】：

我正在尝试在 R 中运行查询以检查两个不同子版块之间的共享评论者。但是，我不断收到以下错误：

警告：postgresqlExecStatement 中的错误：RS-DBI 驱动程序：（无法检索结果：错误：列引用“subreddit”不明确 )

任何想法我哪里出错了？

query <- sprintf("
SELECT final.subreddit_a, final.subreddit_b 
FROM 
  (SELECT a.subreddit AS subreddit_a, 
          a.authors AS authors_in_sub_a, 
          b.subreddit AS subreddit_b, 
          b.authors AS authors_in_sub_b, 
          floor(100 * (count(*)/((a.authors + b.authors)/2))) AS percentage 
  FROM
    (SELECT t1.author AS author, 
            t1.subreddit AS subreddit, 
            t2.authors AS authors
    FROM 
      (SELECT DISTINCT author, subreddit 
      FROM %s 
      WHERE %s author!='[deleted]') AS t1
      JOIN 
        (SELECT * 
        FROM 
          (SELECT subreddit, count(distinct author) AS authors 
          FROM %s 
          WHERE %s author!='[deleted]' GROUP BY subreddit) AS t5 
          WHERE authors >= %s) AS t2
      ON t1.subreddit=t2.subreddit
      GROUP BY subreddit, author) AS a
    JOIN 
      (SELECT t3.author AS author, 
              t3.subreddit AS subreddit, 
              t4.authors AS authors
      FROM 
        (SELECT DISTINCT author, subreddit 
        FROM %s 
        WHERE %s author!='[deleted]') AS t3
        JOIN 
          (SELECT * 
          FROM 
            (SELECT subreddit, count(distinct author) AS authors 
            FROM %s 
            WHERE %s author!='[deleted]' GROUP BY subreddit) AS t6 
          WHERE authors >= %s) AS t4
        ON t3.subreddit=t4.subreddit
        GROUP BY subreddit, author) AS b
      ON a.author=b.author
    WHERE a.subreddit!=b.subreddit GROUP BY 1,3) AS final
  WHERE final.percentage > %s;"

【问题讨论】：

用它的源来限定查询中 subreddit 字段的每次使用就足够了。现在有时你会这样做（例如 a.subreddit），但至少有一些没有别名|表名的用途。
pgsql return table ERROR: column reference is ambiguous的可能重复

标签： postgresql return ambiguous

【解决方案1】：

写table_name.subreddit 而不是subreddit。

【讨论】：

【解决方案2】：

您应该在长选择查询的表名上使用别名

【讨论】：