Question

我有两张桌子：

PERSON列person_id和total
DATA列data_a，data_b，data_c和data_person_id

每个“人”可以在DATA中拥有零个或多个条目 - 您的标准一对多关系。 PERSON的{{1}}列是total中值的总和。目前DATA与total中DATA正确但DATA错误的total中的实际条目之间存在一些差异。

这是我用来查找差异的查询：

SELECT
  person_id
FROM PERSON JOIN (
  SELECT
    data_person_id,
    SUM( data_a + data_b + data_c ) as data_total
  FROM
    DATA
  GROUP BY
    data_person_id
  ) x ON data_person_id = person_id
WHERE
  person_total != data_total

我打算通过Hibernate作为查询，其中后端将是Postgres 9.x.

我正在尝试理解/修复的错误查询是：

UPDATE
  ONLY PERSON
SET
  total = data_info.calc_total
FROM (
  SELECT
    SUM( data_a + data_b + data_c ) as calc_total
  FROM
    DATA
  WHERE
    DATA.data_person_id = person_id
  GROUP BY
    DATA.data_person_id
) as data_info
WHERE
  PERSON.person_id IN (
    SELECT
      data_person_id
    FROM PERSON JOIN (
      SELECT
        data_person_id,
        SUM( data_a + data_b + data_c ) as data_total
      FROM
        DATA
      GROUP BY
        data_person_id
      ) x ON person_id = data_person_id
    WHERE
      total != data_total
  )

现在，由于WHERE DATA.data_person_id = person_id，它无法运行。但如果我把它拿出来，就会使用错误的值。

以下似乎有效，但我对原因感到困惑：

UPDATE
  ONLY PERSON
SET
  total = data_info.calc_total
FROM 
  PERSON P JOIN (
    SELECT
      data_person_id,
      SUM( data_a + data_b + data_c ) as calc_total
    FROM
      DATA
    WHERE
      DATA.data_person_id = person_id
    GROUP BY
      DATA.data_person_id
  ) as data_info ON P.person_id = data_person_id
WHERE
  PERSON.person_id IN (
    SELECT
      data_person_id
    FROM PERSON JOIN (
      SELECT
        data_person_id,
        SUM( data_a + data_b + data_c ) as data_total
      FROM
        DATA
      GROUP BY
        data_person_id
      ) x ON person_id = data_person_id
    WHERE
      total != data_total
  )

我相信我的问题在于我对doc的误解（我猜测自我加入的部分）。

此外，任何改善此查询的方法都值得赞赏！

Answer 1

这是普通的语法UPDATE...FROM。因此，除了WHERE

之外，请使用您的上一个查询

UPDATE
  ONLY PERSON
SET
  total = data_info.calc_total
FROM 
  PERSON P JOIN (
    SELECT
      data_person_id,
      SUM( data_a + data_b + data_c ) as calc_total
    FROM
      DATA
    WHERE
      DATA.data_person_id = person_id
    GROUP BY
      DATA.data_person_id
  ) as data_info ON P.person_id = data_person_id

Answer 2

似乎您的查询是复杂的。任务应该简单：

UPDATE person p
SET    total = d.calc_total
FROM (
  SELECT data_person_id, sum(data_a + data_b + data_c) as calc_total
  FROM   data
  GROUP  BY 1
) d
WHERE  p.person_id = d.data_person_id
AND    p.total IS DISTINCT FROM d.calc_total;

calc_total表中的第一个汇总data，按data_person_id分组。
然后在UPDATE的FROM子句中使用此子查询。
我使用IS DISTINCT FROM来确保覆盖NULL值，而只更改的行实际更新。
如果定义了所有相关列NOT NULL，则可以改为使用=。

-> sqlfiddle demo.

更新子查询中的数据

2 个答案: