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删除冗余的SQL代码

2019-05-19 00:07:34 作者：互联网

码

下面的代码计算线性回归的斜率和截距,以防止数据泄漏.然后,它将方程y = mx b应用于相同的结果集,以计算每行的回归线的值.

如何连接两个查询,以便在不执行WHERE子句两次的情况下计算数据及其斜率/截距？

问题的一般形式是：

SELECT a.group, func(a.group, avg_avg)
FROM a
    (SELECT AVG(field1_avg) as avg_avg
     FROM (SELECT a.group, AVG(field1) as field1_avg
           FROM a
           WHERE (SOME_CONDITION)
           GROUP BY a.group) as several_lines -- potentially
    ) as one_line -- always
WHERE (SOME_CONDITION)
GROUP BY a.group -- again, potentially several lines

我有两次执行SOME_CONDITION.如下所示(使用STRAIGHT_JOIN优化更新)：

SELECT STRAIGHT_JOIN
  AVG(D.AMOUNT) as AMOUNT,
  Y.YEAR * ymxb.SLOPE + ymxb.INTERCEPT as REGRESSION_LINE,
  Y.YEAR as YEAR,
  MAKEDATE(Y.YEAR,1) as AMOUNT_DATE,
  ymxb.SLOPE,
  ymxb.INTERCEPT,
  ymxb.CORRELATION,
  ymxb.MEASUREMENTS
FROM
  CITY C,
  STATION S,
  STATION_DISTRICT SD,
  YEAR_REF Y,
  MONTH_REF M,
  DAILY D,
  (SELECT
    SUM(MEASUREMENTS) as MEASUREMENTS,

    ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) /
    (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE,

    ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) -
    (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) /
    (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT,

    ((avg(t.AMOUNT * t.YEAR)) - avg(t.AMOUNT) * avg(t.YEAR)) /
    (stddev( t.AMOUNT ) * stddev( t.YEAR )) as CORRELATION
  FROM (
    SELECT STRAIGHT_JOIN
      COUNT(1) as MEASUREMENTS,
      AVG(D.AMOUNT) as AMOUNT,
      Y.YEAR as YEAR
    FROM
      CITY C,
      STATION S,
      STATION_DISTRICT SD,
      YEAR_REF Y,
      MONTH_REF M,
      DAILY D
    WHERE
      -- For a specific city ...
      --
      $X{ IN, C.ID, CityCode } AND

      -- Find all the stations within a specific unit radius ...
      --
      6371.009 *
      SQRT(
        POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) +
        (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) *
         POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) ) <= $P{Radius} AND

      SD.ID = S.STATION_DISTRICT_ID AND

      -- Gather all known years for that station ...
      --
      Y.STATION_DISTRICT_ID = SD.ID AND

      -- The data before 1900 is shaky; insufficient after 2009.
      --
      Y.YEAR BETWEEN 1900 AND 2009 AND

      -- Filtered by all known months ...
      --
      M.YEAR_REF_ID = Y.ID AND

      -- Whittled down by category ...
      --
      M.CATEGORY_ID = $P{CategoryCode} AND

      -- Into the valid daily climate data.
      --
      M.ID = D.MONTH_REF_ID AND
      D.DAILY_FLAG_ID <> 'M'
    GROUP BY
      Y.YEAR
  ) t
) ymxb
WHERE
  -- For a specific city ...
  --
  $X{ IN, C.ID, CityCode } AND

  -- Find all the stations within a specific unit radius ...
  --
  6371.009 *
  SQRT(
    POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) +
    (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) *
     POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) ) <= $P{Radius} AND

  SD.ID = S.STATION_DISTRICT_ID AND

  -- Gather all known years for that station ...
  --
  Y.STATION_DISTRICT_ID = SD.ID AND

  -- The data before 1900 is shaky; insufficient after 2009.
  --
  Y.YEAR BETWEEN 1900 AND 2009 AND

  -- Filtered by all known months ...
  --
  M.YEAR_REF_ID = Y.ID AND

  -- Whittled down by category ...
  --
  M.CATEGORY_ID = $P{CategoryCode} AND

  -- Into the valid daily climate data.
  --
  M.ID = D.MONTH_REF_ID AND
  D.DAILY_FLAG_ID <> 'M'
GROUP BY
  Y.YEAR

题

如何每个查询只执行一次重复位,而不是两次？重复的代码：

  $X{ IN, C.ID, CityCode } AND
  6371.009 *
  SQRT(
    POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) +
    (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) *
     POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) ) <= $P{Radius} AND
  SD.ID = S.STATION_DISTRICT_ID AND
  Y.STATION_DISTRICT_ID = SD.ID AND
  Y.YEAR BETWEEN 1900 AND 2009 AND
  M.YEAR_REF_ID = Y.ID AND
  M.CATEGORY_ID = $P{CategoryCode} AND
  M.ID = D.MONTH_REF_ID AND
  D.DAILY_FLAG_ID <> 'M'
GROUP BY
  Y.YEAR

更新1

使用变量和拆分查询似乎允许缓存启动,因为它现在在3.5秒内运行,而它曾经在7中运行.但是,如果有任何方法可以删除重复的代码,我将不胜感激救命.

更新2

上面的代码不能在JasperReports中运行,而VIEW虽然可能是一个修复,但可能效率极低(因为WHERE子句是参数化的).

更新3

使用Unreason对Pythagorean公式的建议和收敛的经线来验证距离：

  6371.009 *
  SQRT(
    POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) +
    (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) *
    POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) )

(这与问题无关,但是其他人想知道…)

更新4

如图所示,代码在JasperReports中运行,针对MySQL数据库运行. JasperReports不允许变量或多个查询.

更新5

我正在寻找一个干净利落的解决方案. ;-)我已经写了一些部分工作的解决方案,但令人遗憾的是,MySQL并不理解部分正确.请参阅与Unreason的讨论,了解几乎可行的答案.

更新6

我可能能够重用第一个WHERE子句中的变量并将它们与第二个进行比较(从而消除了一些重复 – 对$P {}值的检查),但我真的希望删除重复.

更新7

比较YEAR子句,如前一次更新中所假设的,消除重复的BETWEEN,不起作用.

有关

How to eliminate duplicate calculation in SQL?

谢谢！

解决方法:

您应该能够一次性获得所需的一切：

 SELECT
    AVG(D.AMOUNT) as AMOUNT,
    Y.YEAR as YEAR,
    MAKEDATE(Y.YEAR,1) as AMOUNT_DATE,
    Y.YEAR * ymxb.SLOPE + ymxb.INTERCEPT as REGRESSION_LINE,             
    ((avg(AVG(D.AMOUNT) * Y.YEAR)) - avg(AVG(D.AMOUNT)) * avg(Y.YEAR)) /                  
    (stddev( AVG(D.AMOUNT) ) * stddev( Y.YEAR )) as CORRELATION,                     
    ((sum(Y.YEAR) * sum(AVG(D.AMOUNT))) - (count(1) * sum(Y.YEAR * AVG(D.AMOUNT)))) /
    (power(sum(Y.YEAR), 2) - count(1) * sum(power(Y.YEAR, 2))) as SLOPE,   
    ((sum( Y.YEAR ) * sum( Y.YEAR * AVG(D.AMOUNT) )) -
    (sum( AVG(D.AMOUNT) ) * sum(power(Y.YEAR, 2)))) / 
    (power(sum(Y.YEAR), 2) - count(1) * sum(power(Y.YEAR, 2))) as INTERCEPT
 FROM
    CITY C,
    STATION S,
    YEAR_REF Y,
    MONTH_REF M,
    DAILY D
 WHERE
    $X{ IN, C.ID, CityCode } AND
    SQRT(
        POW( C.LATITUDE - S.LATITUDE, 2 ) +
        POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND
    S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND
    Y.YEAR BETWEEN 1900 AND 2009 AND
    M.YEAR_REF_ID = Y.ID AND
    M.CATEGORY_ID = $P{CategoryCode} AND
    M.ID = D.MONTH_REF_ID AND
    D.DAILY_FLAG_ID <> 'M'
 GROUP BY
    Y.YEAR

这些东西不能直接从上面的查询中工作(它具有无意义的组合聚合和其他错误);这是检查公式的好时机

如果您决定进行子查询,请简化公式,然后：

>你可以抓住(你抓住)最内层查询中的所有必要数据,你不必再重复外部查询中的所有表格(只需选择t中的相关列,它们已经在你的处置)
>你不必重复where条件

标签：mysql,sql,postgresql,ireport,code-duplication
来源： https://codeday.me/bug/20190518/1130229.html