Necesito unirme a dos entidades en cinco columnas y necesito AGRUPAR POR cada columna en SELECCIONAR más obtener un RECUENTO en cada GRUPO POR. Si bien esto es sencillo para mí en SQL, estoy irremediablemente confundido con cada ejemplo que puedo encontrar para LINQ.

He encontrado las siguientes dos preguntas (C # Linq Group By en varias columnas [duplicado] yAgrupar por múltiples columnas) que son similares a los míos pero todavía estoy confundido acerca de cómo hacer esto. Aquí está mi declaración SQL:

SELECT  o.org_hq_name,
        o.org_command_name,
        o.org_region_name,
        o.org_installation_name,
        o.org_site_name,
        o.org_subsite_name,
        o.org_hq_id,
        o.org_command_id,
        o.org_region_id,
        o.org_installation_id,
        o.org_site_id,
        count(org_site_id) AS count

FROM    organization o, asset a

WHERE      o.org_hq_id = hq_org_id
AND        o.org_command_id = a.command_org_id
AND        o.org_region_id = a.region_org_id
AND        o.org_installation_id = a.installation_org_id
AND        o.org_site_id = a.site_org_id

GROUP BY o.org_hq_name,
        o.org_command_name,
        o.org_region_name,
        o.org_installation_name,
        o.org_site_name,
        o.org_subsite_name,
        o.org_hq_id,
        o.org_command_id,
        o.org_region_id,
        o.org_installation_id,
        o.org_site_id

Tengo una combinación a continuación:

var join1 =  from m in context.asset
             join o in context.organization
             on new {hqID = a.hq_org_id, commandID = a.command_org_id, regionID = a.region_org_id, installationID = a.installation_org_id, siteID = a.site_org_id}
             equals new {hqID = o.hq_id, commandID = o.command_id, regionID = o.region_id, installationID = o.installation_id, siteID = o.site_id}
             select new
             {
                 hqID = o.hq_id,
                 commandID = o.command_id,
                 regionID = o.region_id,
                 installationID = o.installation_id,
                 siteID = o.site_id
                 //hqId = o.count(org_site_id) AS count
             };

Tengo un grupo a continuación:

var group1 = from a in context.asset
            group a by new
            {
                a.hq_org_id,
                a.command_org_id,
                a.region_org_id,
                a.installation_org_id,
                a.site_org_id

                // I am not sure how to get the count

            } into asset
            select new
            {
                // I cannot figure out how to join
            }

Por favor, ayúdame con la sintaxis de GROUP BY con un JOIN en dos tablas, pero en MÚLTIPLES columnas de las dos tablas Y obtenga el recuento de cada grupo.