Question

我有数组编号= {2,3,4,5,6}

现在我必须从表“dtlRecord”中选择行，其中这个数字是一列。

Number count
2      10
3      23
4      20

所以我需要的是

select sum(count) from dtlRecord where number in (2,3,4,5,6) group by number

我需要LINQ to SQL中的上述查询

Answer 1

使用Enumerable.Contains：

int[] numbers = new[] { 2, 3, 4, 5, 6 };
var query = from r in dtlRecords
            where numbers.Contains(r.Number)
            group r by r.Number into g
            select new {
                Number = g.Key,
                Sum = g.Sum(r => r.Count)
            };

foreach(var result in query) {
    Console.WriteLine("Number = {0}, Sum = {1}", result.Number, result.Sum);
}

Answer 2

LINQ等效于IN
http://www.onedotnetway.com/linq-equivalent-of-where-in/

Answer 3

如何使用内连接：

int[] numbers = new[] { 2, 3, 4, 5, 6 };

from r in dtlRecord
join number in numbers on r.Number equals number
group r by r.Number into g
        select new {
            Number = g.Key,
            Sum = g.Sum(r => r.Count)
        };

或

dtlRecord
    .Join(numbers, r => r.Number, number => number, (r, number) => new {r, number})
    .GroupBy(arg => arg.r.Number, arg => arg.r)
    .Select(g => new
    {
        Number = g.Key,
        Sum = g.Sum(r => r.Count)
    });

在LINQ中使用数组查询的位置

3 个答案: