LINQ : Distinct and Orderby

问题

I am trying to use LINQ (to EF) to get a DISTINCT list and then sort it. All the examples I found sort the result based on the DISTINCT value. But I want to sort it on a different field.

Example: Table with 2 fields (canvasSize and canvasLength);

var sizes = (from s in ent.competitors                         
             select s.canvasSize).Distinct().OrderBy(x => x);

All the examples I found give this type of answer. But it sorts by canvasSize whereas, I want to sort by canvasLength.

I'm stuck ... Any tips are greatly appreciated ...

Per J. Skeet > Additional info:

company  canvasSize  canvasLength

abc       8x10         8
d         8x10         8
e         10x10        10
f         10x10        10
g         40x40        40

I would like it to be distinct on canvasSize. The problem is that when sorted, it results in this order:

10x10
40x40
8x10

I would like the same result set but sorted using canvasLength so the result is:

8x10
10x10
40x40

回答1:

I think what you're after may be something like this:

var sizes = (from s in ent.competitors                         
             select new { s.canvasSize, s.canvasLength })
            .Distinct()
            .OrderBy(x => x.canvasLength);

Update

Based on the extra information in your question, the following should do what you want:

var sizes = ent.competitors
               .Select(c => new {c.canvasSize, c.canvasLength})
               .Distinct()
               .OrderBy(x => x.canvasLength)
               .Select(x => x.CanvasSize)

回答2:

var sizes = ent.competitors
               .GroupBy(s => s.canvasSize)
               .Select(g => g.First())
               .OrderBy(s => s.canvasLength);

来源：https://stackoverflow.com/questions/14636142/linq-distinct-and-orderby

标签

linq

sql-order-by

distinct