How do you group by multiple columns in LINQ TO SQL?
db.Table.GroupBy(a => a.column1.ToString() + a.column2.ToString())
It seems ugly and with poor performance, and I don't even know if it works. Which is the right way to do it?
views:
966answers:
1
+4
A:
try grouping by an anonymous type:
group by new { item.Col1, item.Col2 }
you'll then be able to access Key.Col1, etc
David Hedlund
2009-07-10 14:24:37
Does it works? AnonTypes implement Equals and GetHashCode automatically so you don't have to worry about it?
Jader Dias
2009-07-10 14:26:46
Just tested it, and you're right. Test code: var a = new { A = 1, B = 2 }; var b = new { A = 1, B = 2 }; var c = new { A = 1, B = 3 }; Assert.AreEqual(a, b); Assert.AreNotEqual(a, c);
Jader Dias
2009-07-10 14:28:23
yeah it works, it's the official way. here's a good reference: http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx
David Hedlund
2009-07-10 14:31:11