SQL查询到实体的Linq-C＃

Question

I have been trying to convert this SQL statement into a linq as i am trying to move the functionality into a program.

Here is the SQL statement

SELECT cust.sg_group_name                     AS customer, 
   (SELECT Sum(du.used_space) 
    FROM   sg_groups AS clnt 
           LEFT JOIN client_disk_usage AS du 
                  ON clnt.sg_group_id = du.sg_group_id 
                     AND clnt.group_role_id = 3 
    WHERE  clnt.parent_group_id = cust.sg_group_id 
           AND du.day_of_month = 15 
           AND du.month_of_year = 05 
           AND du.used_space_year = 2016) AS disk_usage 
FROM   sg_groups AS cust 
WHERE  cust.group_role_id = 2 
ORDER  BY cust.sg_group_name 

Essentially the output is just a list with two columns

customer      disk_usage
Customer1    136401537652 
Customer2    42208008210 

If possible i just want to convert this to a linq statement. I have tried putting the query into LinqPad, but it doesn't seem to want to convert from SQL to Linq (just comes up with a blank white page). I have had a crack at the query myself, but i either get something that doesn't work altogether, or an incorrect number of results.

If anyone has any suggestions that would be great!

Answer 1

disk_usage(Sub Query) is a bit Complicated Part. Converted over here. Try this out

var CoreList = (from clnt in EntityName.sg_groups 
                    join du in EntityName.client_disk_usage 
                    on new { GrpId = clnt.sg_group_id, RoleId = clnt.group_role_id } equals new { GrpId = du.sg_group_id, RoleId = 3 } into LJ
                    from RT in LJ.DefaultIfEmpty()
                    where du.day_of_month == 15 && du.month_of_year == 05 && du.used_space_year == 2016
                    select new {clnt, du, RT}
                   ).ToList();

    var CoreListSet = CoreList.Select(i=> new YourEntityClass
                      {
                      //Fetch the ParentGroupId & UsedSpace
                      }).ToList();

    var CoreListComplete = (from cl in CoreListSet 
                           join cust in EntityName.sg_groups 
                           on cust.sg_group_id equals cl.parent_group_id).ToList();

Now get the sum of CoreListComplete & just implement the base Select Query in Linq!

Answer 2

Apologies for the delayed response. I've marked @Anil answer up as this is the one that helped me find the answer. You solution did work @Sathish but it can be accomplished in a single command. Here is my final solution. Many thanks for your help!

storeGridUsage = (
                from cust in db.sg_groups
                from client in db.sg_groups
                join du in db.client_disk_usage on client.SG_GROUP_ID equals du.SG_GROUP_ID
                where client.GROUP_ROLE_ID == 3
                where client.PARENT_GROUP_ID == cust.SG_GROUP_ID && du.DAY_OF_MONTH == day && du.MONTH_OF_YEAR == month && du.USED_SPACE_YEAR == year
                where cust.GROUP_ROLE_ID == 2
                orderby cust.SG_GROUP_NAME
                group new {cust, du} by cust.SG_GROUP_NAME
                into g
                select new StoreGridUsage
                {
                    CustomerName = g.Key,
                    DiskUsageInBytes = g.Sum(o => o.du.USED_SPACE)
                }).ToList();