How to use group by only for some columns in sql Query? - sql

Question

The following query returns 550 records, which I am then grouping by some columns in the controller via linq. However, how can I achieve the "group by" logic in the SQL query itself? Additionally, post-grouping, I need to show only 150 results to the user.
Current SQL query:
SELECT DISTINCT
l.Id AS LoadId
, l.LoadTrackingNumber AS LoadDisplayId
, planningType.Text AS PlanningType
, loadStatus.Id AS StatusId
, loadWorkRequest.Id AS LoadRequestId
, loadStatus.Text AS Status
, routeIds.RouteIdentifier AS RouteName
, planRequest.Id AS PlanId
, originPartyRole.Id AS OriginId
, originParty.Id AS OriginPartyId
, originParty.LegalName AS Origin
, destinationPartyRole.Id AS DestinationId
, destinationParty.Id AS DestinationPartyId
, destinationParty.LegalName AS Destination
, COALESCE(firstSegmentLocation.Window_Start, originLocation.Window_Start) AS StartDate
, COALESCE(firstSegmentLocation.Window_Start, originLocation.Window_Start) AS BeginDate
, destLocation.Window_Finish AS EndDate
AS Number
FROM Domain.Loads (NOLOCK) AS l
INNER JOIN dbo.Lists (NOLOCK) AS loadStatus ON l.LoadStatusId = loadStatus.Id
INNER JOIN Domain.Routes (NOLOCK) AS routeIds ON routeIds.Id = l.RouteId
INNER JOIN Domain.BaseRequests (NOLOCK) AS loadWorkRequest ON loadWorkRequest.LoadId = l.Id
INNER JOIN Domain.BaseRequests (NOLOCK) AS planRequest ON planRequest.Id = loadWorkRequest.ParentWorkRequestId
INNER JOIN Domain.Schedules AS planSchedule ON planSchedule.Id = planRequest.ScheduleId
INNER JOIN Domain.Segments (NOLOCK) os on os.RouteId = routeIds.Id AND os.[Order] = 0
INNER JOIN Domain.LocationDetails (NOLOCK) AS originLocation ON originLocation.Id = os.DestinationId
INNER JOIN dbo.EntityRoles (NOLOCK) AS originPartyRole ON originPartyRole.Id = originLocation.DockRoleId
INNER JOIN dbo.Entities (NOLOCK) AS originParty ON originParty.Id = originPartyRole.PartyId
INNER JOIN Domain.LocationDetails (NOLOCK) AS destLocation ON destLocation.Id = routeIds.DestinationFacilityLocationId
INNER JOIN dbo.EntityRoles (NOLOCK) AS destinationPartyRole ON destinationPartyRole.Id = destLocation.DockRoleId
INNER JOIN dbo.Entities (NOLOCK) AS destinationParty ON destinationParty.Id = destinationPartyRole.PartyId
INNER JOIN dbo.TransportationModes (NOLOCK) lictm on lictm.Id = l.LoadInstanceCarrierModeId
INNER JOIN dbo.EntityRoles (NOLOCK) AS carrierPartyRole ON lictm.CarrierId = carrierPartyRole.Id
INNER JOIN dbo.Entities (NOLOCK) AS carrier ON carrierPartyRole.PartyId = carrier.Id
INNER JOIN dbo.EntityRoles (NOLOCK) AS respPartyRole ON l.ResponsiblePartyId = respPartyRole.Id
INNER JOIN dbo.Entities (NOLOCK) AS respParty ON respPartyRole.PartyId = respParty.Id
INNER JOIN Domain.LoadOrders (NOLOCK) lo ON lo.LoadInstanceId = l.Id
INNER JOIN Domain.Orders (NOLOCK) AS o ON lo.OrderInstanceId = o.Id
INNER JOIN Domain.BaseRequests (NOLOCK) AS loadRequest ON loadRequest.LoadId = l.Id
--Load Start Date
LEFT JOIN Domain.Segments (NOLOCK) AS segment ON segment.RouteId = l.RouteId AND segment.[Order] = 0
LEFT JOIN Domain.LocationDetails (NOLOCK) AS firstSegmentLocation ON firstSegmentLocation.Id = segment.DestinationId
LEFT JOIN dbo.Lists (NOLOCK) AS planningType ON l.PlanningTypeId = planningType.Id
LEFT JOIN dbo.EntityRoles (NOLOCK) AS billToRole ON o.BillToId = billToRole.Id
LEFT JOIN dbo.Entities (NOLOCK) AS billTo ON billToRole.PartyId = billTo.Id
WHERE o.CustomerId in (34236) AND originLocation.Window_Start >= '07/19/2015 00:00:00' AND originLocation.Window_Start < '07/25/2015 23:59:59' AND l.IsHistoricalLoad = 0
AND loadStatus.Id in (285, 286,289,611,290)
AND loadWorkRequest.ParentWorkRequestId IS NOT NULL
AND routeIds.RouteIdentifier IS NOT NULL
AND (planSchedule.EndDate IS NULL OR (planSchedule.EndDate is not null and CAST(CONVERT(varchar(10), planSchedule.EndDate,101) as datetime) > CAST(CONVERT(varchar(10),GETDATE(),101) as datetime))) ORDER BY l.Id DESC
linq:
//Get custom grouped data
var loadRequest = (from lq in returnList
let loadDisplayId = lq.LoadDisplayId
let origin = lq.OriginId //get this origin for route
let destination = lq.DestinationId // get this destination for route
group lq by new
{
RouteId = lq.RouteName,
PlanId = lq.PlanId,
Origin = lq.OriginId,
Destination = lq.DestinationId
}
into grp
select new
{
RouteId = grp.Key.RouteId,
PlanId = grp.Key.PlanId,
Origin = grp.Key.Origin,
Destination = grp.Key.Destination,
Loads = (from l in grp select l)
}).OrderBy(x => x.Origin).ToList();

Answer 1

I'm guessing you want to Group By column 1 but include columns 2 and 3 in your Select. Using a Group By you cannot do this. However, you can do this using a T-SQL Windowing function using the OVER() operator. Since you don't say how you want to aggregate, I cannot provide an example. But look at T-SQL Windowing functions. This article might help you get started.

Answer 2

One important thing you need to understand about GROUP BY is that you must assume that there are multiple values in every column outside of the GROUP BY list. In your case, you must assume that for each value of Column1 there would be multiple values of Column2 and Column3, all considered as a single group.
If you want your query to process any of these columns, you must specify what to do about these multiple values.
Here are some choices you have:
Pick the smallest or the largest value for a column in a group - use MIN(...) or MAX(...) aggregator for that
Count non-NULL items in a group - use COUNT(...)
Produce an average of non-NULL values in a group - use AVG(...)
For example, if you would like to find the smallest Column2 and an average of Column3 for each value of Column1, your query would look like this:
select
Column1, MIN(Column2), AVG(Column3)
from
TableName
group by
Column1