使用win 7上SQL Server 2008R2中另一个表中的列计算填充表列

我需要在Win7上的SQLServer2008R2中填充一个表列

表1

Id1    Id2   value1    
---------------------
1       a      58218    
1       b       2888       
1       c       916        

我需要创建一个表2，以便

Id1    value1    value1_b_over_a      value1_c_over_a
------------------------------------------------------
1       58218     2888/58218                916/58218 

我希望只使用一个SQL查询获取表

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任何帮助都将不胜感激

您可以通过条件聚合来实现这一点：

select t1.id1,
       sum(case when id2 = 'a' then value1 end) as value1,
       sum(case when id2 = 'b' then value1 end) / sum(case when id2 = 'a' then value1 end) as value1_b_over_a,
       sum(case when id2 = 'c' then value1 end) / sum(case when id2 = 'a' then value1 end) as value1_c_over_a,
from table1 t1
group by t1.id1;

注意：SQLServer执行整数运算。如果需要数字，请将

value1

转换为适当的数字类型

select t1.id1,
       sum(case when id2 = 'a' then value1 end) as value1,
       sum(case when id2 = 'b' then cast(value1 as float) end) / sum(case when id2 = 'a' then value1 end) as value1_b_over_a,
       sum(case when id2 = 'c' then cast(value1 as float) end) / sum(case when id2 = 'a' then value1 end) as value1_c_over_a,
from table1 t1
group by t1.id1;

---

您可以先做一个简单的枢轴，然后再进行操作

select result.id1,
    result.a value1,
    cast(result.b as decimal) / result.a value1_b_over_a,
    cast(result.c as decimal) / result.a value1_c_over_a
from (
    select *
    from table1 t
    pivot(sum(value1) for id2 in (
                [a],
                [b],
                [c]
                )) as pivotrow
    ) result;