Converting an SQL query in to LINQ C#

Question

I've an SQL Query:

SELECT 
      node.GroupName
    , depth = COUNT(parent.GroupName) - 1
FROM CompanyGroup node
JOIN CompanyGroup parent ON node.LeftID BETWEEN parent.LeftID AND parent.RightID
GROUP BY node.GroupName, node.LeftID
ORDER BY node.LeftID;

I've tried converting it to LINQ myself but I'm unfamiliar with the language, after some research I've tried using Linqer but it won't convert the functions 'BETWEEN' or 'COUNT'.

The closest I've gotten so far is:

        var groupModel =
            from node in db.CompanyGroups
            join parent in db.CompanyGroups.Where(node.LeftID > parent.LeftID && node.LeftID < parent.RightID)
            orderby node.LeftID
            select node.GroupName;

which doesn't work and wouldn't return the 'depth' even if it did, help please!

Edit:

The query is used to return the depth of nodes in a nested set in an order so that I can create a representation of a hierarchy; I'm following this tutorial: http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/ on the chapter 'Finding the Depth of the Nodes'

Answer 1

This should get you close.

Given

        var companyGroups = new List<CompanyGroup>
        {
            new CompanyGroup {GroupName = "ELECTRONICS",            LeftID = 1 , RightID =20 },
            new CompanyGroup {GroupName = "TELEVISIONS",            LeftID = 2 , RightID =9  },
            new CompanyGroup {GroupName = "TUBE",                   LeftID = 3 , RightID =4  },
            new CompanyGroup {GroupName = "LCD",                    LeftID = 5 , RightID =6  },
            new CompanyGroup {GroupName = "PLASMA              ",   LeftID = 7 , RightID =8  },
            new CompanyGroup {GroupName = "PORTABLE ELECTRONICS",   LeftID =10 , RightID =19 },
            new CompanyGroup {GroupName = "MP3 PLAYERS         ",   LeftID =11 , RightID =14 },
            new CompanyGroup {GroupName = "FLASH               ",   LeftID =12 , RightID =13 },
            new CompanyGroup {GroupName = "CD PLAYERS          ",   LeftID =15 , RightID =16 },
            new CompanyGroup {GroupName = "2 WAY RADIOS        ",   LeftID =17 , RightID =18   },
        };

then this

        var results = from node in companyGroups
                      from parent in companyGroups
                      where node.LeftID >= parent.LeftID && node.RightID <= parent.RightID
                      group node by node.GroupName into g
                      orderby g.First().LeftID
                      select new { GroupName = g.Key, Depth = g.Count() - 1 };

yields

{ GroupName = ELECTRONICS, Depth = 0 }

{ GroupName = TELEVISIONS, Depth = 1 }

{ GroupName = TUBE, Depth = 2 }

{ GroupName = LCD, Depth = 2 }

{ GroupName = PLASMA              , Depth = 2 }

{ GroupName = PORTABLE ELECTRONICS, Depth = 1 }

{ GroupName = MP3 PLAYERS         , Depth = 2 }

{ GroupName = FLASH               , Depth = 3 }

{ GroupName = CD PLAYERS          , Depth = 2 }

{ GroupName = 2 WAY RADIOS        , Depth = 2 }