計算基於mysql中的行內容的數學計算

我是相對較新的Mysql，並試圖找出一種方法來做一個簡單的數學計算行之間，下面是我正在使用的視圖的樣本，我想計算很少基本功能計算基於mysql中的行內容的數學計算

 

+-----------------+-------+-------+------------+ 
| Buy_cty_rgn | total | Sntmt | Sntmt_Calc | 
+-----------------+-------+-------+------------+ 
| Central Chennai | 24 | D  |   | 
| Central Chennai | 11 | I  |   | 
| Central Chennai |  2 | S  |   | 
| Central Chennai | 37 | All |   | 
| North Chennai | 11 | D  |   | 
| North Chennai | 17 | I  |   | 
| North Chennai |  2 | S  |   | 
| North Chennai | 30 | All |   | 
| South Chennai | 113 | D  |   | 
| South Chennai | 108 | I  |   | 
| South Chennai | 28 | S  |   | 
| South Chennai | 249 | All |   | 
| West Chennai |  7 | D  |   | 
| West Chennai |  8 | I  |   | 
| West Chennai |  6 | S  |   | 
| West Chennai | 21 | All |   | 
| All    | 337 | All |   | 
+-----------------+-------+-------+------------+

Snt_Calc =（（共其中sntmt = d /總其中sntmt = 所有）* 100） - （（共其中sntmt = 我 /總其中sntmt = 所有）* 100）

所需的輸出

 
+---------+-----------------+-------+-------+------------+ 
| Dmc_Cty | Buy_cty_rgn | total | Sntmt | Calc_Sntmt | 
+---------+-----------------+-------+-------+------------+ 
| Chennai | Central Chennai | 24 | D  |   | 
| Chennai | Central Chennai | 11 | I  |   | 
| Chennai | Central Chennai |  2 | S  |   | 
| Chennai | Central Chennai | 37 | All | 35.14  | 
| Chennai | North Chennai | 11 | D  |   | 
| Chennai | North Chennai | 17 | I  |   | 
| Chennai | North Chennai |  2 | S  |   | 
| Chennai | North Chennai | 30 | All | -20.00  | 
| Chennai | South Chennai | 113 | D  |   | 
| Chennai | South Chennai | 108 | I  |   | 
| Chennai | South Chennai | 28 | S  |   | 
| Chennai | South Chennai | 249 | All | 2.01  | 
| Chennai | West Chennai |  7 | D  |   | 
| Chennai | West Chennai |  8 | I  |   | 
| Chennai | West Chennai |  6 | S  |   | 
| Chennai | West Chennai | 21 | All | -4.76  | 
+---------+-----------------+-------+-------+------------+

來源

2013-12-21 Mysql_NUb_Sri

做計算作爲一個子查詢，然後加入結果回：

查詢計算值：

select Dmc_Cty, Buy_cty_rgn, 
     (100*sum(case when Sntmt = 'D' then total end)/sum(case when Sntmt = 'All' then total end) - 
     100*sum(case when Sntmt = 'I' then total end)/sum(case when Sntmt = 'All' then total end) 
     ) as Calc_Sntmt 
from table t 
group by Dmc_Cty, Buy_cty_rgn;

加入查詢結果返回：

select t.*, (case when t.Sntmt = 'All' then tsum. Calc_Sntmt end) as Calc_Sntmt 
from table t left outer join 
    (select Dmc_Cty, Buy_cty_rgn, 
      (100*sum(case when Sntmt = 'D' then total end)/sum(case when Sntmt = 'All' then total end) - 
       100*sum(case when Sntmt = 'I' then total end)/sum(case when Sntmt = 'All' then total end) 
      ) as Calc_Sntmt 
     from table t 
     group by Dmc_Cty, Buy_cty_rgn 
    ) tsum 
    on tsum.Dmc_Cty = t.Dmc_Cty and 
     tsum.Buy_cty_rgn = t.Buy_cty_rgn;

來源

2013-12-21 16:56:49

您好，戈登，這個代碼就像一個魅力。非常感謝幫助。我有兩個問題，但如果你可以幫忙的話，它會是你的。）我無法理解應用左外連接的邏輯，我可以請你詳細說明它2.）在**之前還有一個額外的** ** **在子查詢中我試圖修改它，但是由於某種原因，我無法在答案上這麼做..如何解決它 - 再次感謝噸，以節省我的皮膚:) –

「total」之前的單引號是一個錯字。「左外連接」並不是真的有必要。它只強調在第一個表中的所有行都保留在輸出中。 –

感謝您的輸入先生，我現在意識到，我想更新現有的表** ** Calc **列輸出，我嘗試了切斷方法做到這一點，但我最終與_Error代碼：1064 您在您的錯誤SQL語法; _我可以尋求您的指導嗎？ –

計算基於mysql中的行內容的數學計算

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