SQL查詢來計算重量或發佈基於價值/重量空

Question

我有列的表格 - ID，X1，X2，X3，X4

如果我有值

1,y,y,y,y 
2,y,null,n,null 
3,y,null,null,null 

然後說，我想計算（1）/ 和顯示行（Y的數量）爲

1,.25,.25,.25,.25 
2,1,0,0,0 
3,1,0,0,0 

是否有可能做到這一點使用SQL查詢？

Answer 1

下面是一個使用子查詢另一個蠻力攻擊。設置一些測試數據：

CREATE TABLE MyTable 
(
    Id int  not null 
    ,Col1 char(1) null 
    ,Col2 char(1) null 
    ,Col3 char(1) null 
    ,Col4 char(1) null 
) 

INSERT MyTable 
      select 1, 'Y', 'Y', 'Y', 'Y' 
union all select 2, 'Y', null, 'N', null 
union all select 3, 'Y', null, null, null 
union all select 4, null, null, null, null 

我用目標值的字符數據，但你應該沒有問題，使其數值。我添加了第四行來檢查除以零（謝謝ps！）。所以，

SELECT 
    mt.ID 
    ,case mt.Col1 when 'Y' then xx.distrib else 0 end 
    ,case mt.Col2 when 'Y' then xx.distrib else 0 end 
    ,case mt.Col3 when 'Y' then xx.distrib else 0 end 
    ,case mt.Col4 when 'Y' then xx.distrib else 0 end 
from MyTable mt 
    inner join (select 
       ID 
       ,1.0/( case Col1 when 'Y' then 1 else 0 end 
         + case Col2 when 'Y' then 1 else 0 end 
         + case Col3 when 'Y' then 1 else 0 end 
         + case Col4 when 'Y' then 1 else 0 end) distrib 
       from MyTable) xx 
    on xx.Id = mt.Id 

似乎產生所需的結果。 （運行在自己的子查詢，你通過零得到一個鴻溝......但老實說，我不知道爲什麼運行整個查詢沒有。

Answer 2

這裏的天真的版本將是

SELECT 
    id, 
    CASE 
    WHEN x1 IS NULL THEN 
     0 
    WHEN f_eval(x1) + f_eval(x2,0) + f_eval(x3,0) + f_eval(x4,0) = 0 THEN 
     -- default value 
    ELSE 
     1/(f_eval(x1) + f_eval(x2,0) + f_eval(x3,0) + f_eval(x4,0)) 
    END, 
    -- repeat for each column 
FROM 
    Table 

其中f_eval被定義爲或多或少如下：

CREATE FUNCTION f_eval(
     @x_value varchar(1) 
BEGIN 

    DECLARE @return_val int 
    SELECT 
     @return_val = 
     case 
     WHEN ISNULL(@x_value, 'n') = 'y' THEN 
      1 
     ELSE 
      0 
     END 

    RETURN @return_val 
END 

Answer 3

嘗試foillowing

select 

(SUM(case when x1 is null then 0 else 1 end))* 1.0/ ((SUM(case when x1 is null then 0 else 1 end) + SUM(case when x2 is null then 0 else 1 end)+ SUM(case when x3 is null then 0 else 1 end) + + SUM(case when x4 is null then 0 else 1 end)) * 1.0), 
(SUM(case when x2 is null then 0 else 1 end))* 1.0/ ((SUM(case when x1 is null then 0 else 1 end) + SUM(case when x2 is null then 0 else 1 end)+ SUM(case when x3 is null then 0 else 1 end) + + SUM(case when x4 is null then 0 else 1 end)) * 1.0), 
(SUM(case when x3 is null then 0 else 1 end))* 1.0/ ((SUM(case when x1 is null then 0 else 1 end) + SUM(case when x2 is null then 0 else 1 end)+ SUM(case when x3 is null then 0 else 1 end) + + SUM(case when x4 is null then 0 else 1 end)) * 1.0), 
(SUM(case when x4 is null then 0 else 1 end))* 1.0/ ((SUM(case when x1 is null then 0 else 1 end) + SUM(case when x2 is null then 0 else 1 end)+ SUM(case when x3 is null then 0 else 1 end) + + SUM(case when x4 is null then 0 else 1 end)) * 1.0) 
from table group by id 

你可能已經確保你不要除以零

編輯2

通過添加更多的情況分母時0，那麼1 你也應該改變

case when x1 is null then 0 else 1 end 

到

case when x1 = 'y' then 1 else 0 end 

Answer 4

試試這個

的樣本數據

declare @t table(Id int,Col1 char(1) null,Col2 char(1) null,Col3 char(1) null,Col4 char(1) null) 
INSERT @t select 1, 'Y', 'Y', 'Y', 'Y' union all select 2, 'Y', null, null, null 
union all select 3, 'Y', null, null, null 

查詢：

select t.id 
,case Col1 when 'Y' then LEFT(cast(1.0/x.cntys as varchar(20)),4) else cast(0 as varchar(1)) end x1 
,case Col2 when 'Y' then LEFT(cast(1.0/x.cntys as varchar(20)),4) else cast(0 as varchar(1)) end x2 
,case Col3 when 'Y' then LEFT(cast(1.0/x.cntys as varchar(20)),4) else cast(0 as varchar(1)) end x3 
,case Col4 when 'Y' then LEFT(cast(1.0/x.cntys as varchar(20)),4) else cast(0 as varchar(1)) end x4 

from @t t 
join(
select ROW_NUMBER() over(order by getdate()) rn, 
    COUNT(col1) + COUNT(col2) + COUNT(col3) + COUNT(col4) cntys from @t 
group by id)X 
on t.Id = X.rn 

輸出：

id x1 x2 x3 x4 
1 0.25 0.25 0.25 0.25 
2 1.00 0 0 0 
3 1.00 0 0 0