Multiple aggregate functions in one query using Linq to SQL [duplicate]

Answer 1

You can use the group by constant trick to get all the aggregates with single SQL query (and shared complicated filter):

var result = dbSet
    .Where( <very complicated conditions> )
    .GroupBy(e => 1) // aribitrary value
    .Select(g => new
    {
        CountA = g.Count(),
        SumB = g.Sum(e => e.EntityB.PropertyB),
        AverageC = g.Average(e => e.EntityC.PropertyC),
    })
    .FirstOrDefault();