Converting a SQL Select Statement with Joins to a LINQtoSQL query

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1.00/5 (1 vote)

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VS2010

I've been trying to transform a SQL Statement (below) to a LINQtoSQL statement. I developed a horrible workaround, but it's incredible inefficient. Does anyone know how to do it without all horribleness?

SQL Select Statement:

SQL

SELECT DISTINCT locationGroups.*
FROM locationGroups
JOIN locations
	ON locationGroups.locationGroupID = locations.locationGroup
JOIN locationRegions
	ON locations.region = locationRegions.regionID
WHERE locationRegions.regionID = 34

My horrible c# code:

C#

public List<locationGroup> GetLocationGroups(locationRegion locationRegion)
        {
            #region Inefficent code

            using (var context = new Entities())
            {
                location[] lA = context.locations.Where(location => location.region == locationRegion.regionID).ToArray();

                List<locationGroup> lG = new List<locationGroup>();

                foreach (location l in lA)
                {
                    if (lG.Any(list => list.locationGroupID == l.locationGroup) == false)
                        lG.Add(context.locationGroups.FirstOrDefault(locationGroup => locationGroup.locationGroupID == l.locationGroup));
                }

                return lG;
            }

            #endregion
        }

Posted 24-Jul-13 12:07pm

Kyle Gottfried

Updated 25-Jul-13 2:20am

v3

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Kyle Gottfried · Accepted Answer · 2013-08-01T09:28:00

I went to Mycroft Holmes suggested site and after awhile I finally built something that worked. I posted the solution below for reference to anyone else who needs help on this issue.

C#

using (var context = new iomniEntities())
            {
                List<locationGroup> lLG = new List<locationGroup>();
                lLG = (from lG in context.locationGroups
                       join l in context.locations on lG.locationGroupID equals l.locationGroup
                       join lR in context.locationRegions on l.region equals lR.regionID
                       where (l.locationTypeID == 9 || l.locationTypeID == 11) && l.active == true && lR.regionID == locationRegion.regionID
                       select lG).Distinct().ToList<locationGroup>();

                return lLG;

            }

Mycroft Holmes · Accepted Answer · 2013-07-24T18:01:00

Solution 1

I find this site most useful when faffing around with linq 101 Linq samples[^]

There are some join examples in there

Posted 24-Jul-13 18:01pm

Mycroft Holmes

Comments

Maciej Los 2-Aug-13 15:09pm

+5!