Question

可能重复：
Get sum of two columns in one LINQ query

我需要知道如何编写一个LINQ查询，它将给出与此SQL查询相同的结果：

select sum(col1) as [col1] , sum(col2) as [col2] , sum(col1)/sum(col2) as [col3], col4 as [col4] 
from some_table 
group by col4

Answer 1

或者使用Lambda，我假设some_table是实体或存储库等等。

some_table.GroupBy( row => row.col4).Select( row => new
{
    col1 = row.Sum(x => x.col1), 
    col2 = row.Sum(x => x.col2),
    col3 = row.Sum(x => x.col1) / row.Sum(x => x.col2),
    col4 = row.Key
});

Answer 2

完整道具转到Steven获取此答案：https://stackoverflow.com/a/2432348/211627

from row in some_table
group row by row.col4 into g
select new
{
    col1 = g.Sum(x => x.col1), 
    col2 = g.Sum(x => x.col2),
    col3 = g.Sum(x => x.col1) / g.Sum(x => x.col2),
    col4 = g.Key
};

Answer 3

这假设您的表是某种实体。这会将它放入Anonymous Type，但也可用于创建自己类型的对象。

myInitialCollection.GroupBy(x => x.Col4).Select(x => 
    new { 
            col1 = x.Sum(y => y.Col1), 
            col2 = x.Sum(y => y.Col2), 
            col3 = (x.Sum(y => y.col1) / x.Sum(y => y.col2)), 
            col4 = x.Key
    });

LINQ group by和SUM

3 个答案: