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c#linqlinq-group

Grouping and summing by Linq

I would like to get the total order amount for each customer with Linq, I know I need to group and sum I have only succeeded to group without summing the whole amount for each order.

var OrderByCustumer = new[] {
        new { name = "cust1", order = 400 },
        new { name = "cust1", order = 250 },
        new { name = "cust1", order = 130 },
        new { name = "cust2", order = 30 },
        new { name = "cust3", order = 205}
     };
    
    var res= OrderByCustumer.GroupBy(x=>x.name).Select((x,y)=>new{
    a=x.Key
    });
    
    foreach(var a in res){
     Console.WriteLine(a);
    }
   

.**
OutPut
a = cust1 
a = cust2 
a = cust3
**
Solution

  • Try this

    var res = OrderByCustumer.GroupBy(x => x.name).Select(x => new {
    a = x.Key,
    sum = x.Sum(c => c.order)
});

foreach (var item in res)
{
    Console.WriteLine($"{ item.a} - Sum = {item.sum}");
}