使用具有聚合功能的LINQ在列上进行SELECT

Question

I'm tring to create a dataset that is only the StatusID from the tbBreadCrumb table after the row that is the max BreadCrumbID is selected but not sure how to do it. Basically, I only want to return StatusID to JSON but I'm getting red underline saying: "int does not contain a definition set for 'Select' and no extension method 'Select' could you be missing an assembly?"

Here's my code:

[WebMethod]
    public static object getMaxBreadCrumbByProjectID(int id)
    {
        using (dbPSREntities5 myEntities = new dbPSREntities5())
        {
            var thisProject = myEntities.tbBreadCrumbs.Where(x => x.ProjectID == id).Max(x => x.BreadCrumbID);

            var columns = thisProject.Select(x => new { x.StatusID }).ToList(); <--- this has the red underline and error message.

            return columns;
        }
    }

Answer 1

As the error is trying to tell you, thisProject is already a number.

Max() returns the highest value, not a collection.

Answer 2

Max returning your Maximum BreadCrumbId which is an integer.Try this:

var id = myEntities.tbBreadCrumbs.Where(x => x.ProjectID == id).Max(x => x.BreadCrumbID);
var columns = myEntities.tbBreadCrumbs.Where(x => x.BreadCrumbID == id)
                                      .Select(x => x.StatusID).ToList();