Question

我正在使用访问权限来运行查询，但这是说不支持联接操作。我已经检查了语法，看起来还不错。谁能帮我理解为什么失败了吗？

library(dplyr)

data_frame <- data_frame %>%
  mutate(
    weights = ifelse(group==1,probs1/probs1,
              ifelse(group==2,probs1/probs2,
              ifelse(group==3,probs1/probs3,
              ifelse(group==4,probs1/probs4,NA))))
  )

print(data_frame)

对于上下文，这是我的表

数据表

SELECT
   d.uid,
   md_20180901.monthval,
   md_20180801.monthval,
   md_20180701.val 
FROM
   (
(data as d 
      LEFT JOIN
         (
            SELECT
               md.* 
            FROM
               monthdata md 
            WHERE
               md.monthval = #01/09/2018# 
         )
         as md_20180901 
         ON d.UID = md_20180901.dataUID 
         AND md_20180901.monthval = #01/09/2018# ) 
      LEFT JOIN
         (
            SELECT
               md.* 
            FROM
               monthdata md 
            WHERE
               md.monthval = #01/08/2018# 
         )
         as md_20180801 
         ON d.UID = md_20180801.dataUID 
         AND md_20180801.monthval = #01/08/2018#
   )
   LEFT JOIN
      (
         SELECT
            md.* 
         FROM
            monthdata md 
         WHERE
            md.monthval = #01/07/2018# 
      )
      as md_20180701 
      ON d.UID = md_20180701.dataUID 
      AND md_20180701.monthval = #01/07/2018#
WHERE
   d.UID = "5B51141D";

月数据表

ID
UID
MYNAME

Answer 1

仅在表达式中包含括号时，Access才支持联接表达式中的文字：

SELECT
   d.uid,
   md_20180901.monthval,
   md_20180801.monthval,
   md_20180701.val 
FROM
   (
(data as d 
      LEFT JOIN
         (
            SELECT
               md.* 
            FROM
               monthdata md 
            WHERE
               md.monthval = #01/09/2018# 
         )
         as md_20180901 
         ON (d.UID = md_20180901.dataUID 
         AND md_20180901.monthval = #01/09/2018#) ) 
      LEFT JOIN
         (
            SELECT
               md.* 
            FROM
               monthdata md 
            WHERE
               md.monthval = #01/08/2018# 
         )
         as md_20180801 
         ON (d.UID = md_20180801.dataUID 
         AND md_20180801.monthval = #01/08/2018#)
   )
   LEFT JOIN
      (
         SELECT
            md.* 
         FROM
            monthdata md 
         WHERE
            md.monthval = #01/07/2018# 
      )
      as md_20180701 
      ON (d.UID = md_20180701.dataUID 
      AND md_20180701.monthval = #01/07/2018#)
WHERE
   d.UID = "5B51141D";

但是，您在这里做的事情很奇怪。您还在比较内部子查询。删除那些：

SELECT
   d.uid,
   md_20180901.monthval,
   md_20180801.monthval,
   md_20180701.val 
FROM
(
(data as d 
      LEFT JOIN
         monthdata as md_20180901 
         ON (d.UID = md_20180901.dataUID 
         AND md_20180901.monthval = #01/09/2018#) ) 
      LEFT JOIN
         monthdata as md_20180801 
         ON (d.UID = md_20180801.dataUID 
         AND md_20180801.monthval = #01/08/2018#)
   )
   LEFT JOIN
      monthdata as md_20180701 
      ON (d.UID = md_20180701.dataUID 
      AND md_20180701.monthval = #01/07/2018#)
WHERE
   d.UID = "5B51141D";

Answer 2

首先删除所有不必要的部分，然后将其简化。示例：

            SELECT
               md.* 
            FROM
               monthdata md 
            WHERE
               md.monthval = #01/09/2018# 
         )
         as md_20180901 
         ON d.UID = md_20180901.dataUID 
         AND md_20180901.monthval = #01/09/2018#

可以简化：

(SELECT val FROM monthdata WHERE monthval=#01/09/2018#) md_20180901
ON d.UID=md_20180901.dataUID

除非字段名称冲突，否则无需重复表名称。您不需要分配永远不会使用的别名（实际上，我通常只在两次使用同一张表的情况下才分配别名）。您不需要在monthval上添加ON进行过滤，因为您已经在WHERE中进行了过滤。您实际收集的唯一字段是val（monthval实际上是一个固定值，因为您要按特定日期进行过滤），因此请不要使用*。

清理查询并尝试一次添加一个monthval，然后看看会发生什么情况。

不支持Access SQL连接表达式

2 个答案: