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Editorial Team
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Asked: 2026-06-08T11:27:51+00:00

I have a Category table which has 3 fields i’m interested in: ID, Name,

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I have a Category table which has 3 fields i’m interested in:

ID, Name, CategoryType

The root nodes are identified by having CategoryType of 1, subnodes of the root nodes are of type 2 and sub-sub nodes are of type 3.

There’s a 2nd table, CategoryRelationship, of which the two columns that matter are:

CategoryID, ParentCategoryID.

What I would like is a listing of records so that we have the name of each category/subcategory and it’s ID, like below

ID RootName1 ID SubName1 ID Sub-SubName1
ID RootName1 ID SubName1 ID Sub-SubName2
ID RootName1 ID SubName2 ID Sub-SubName1
ID RootName1 ID SubName2 ID Sub-SubName2
ID RootName1 ID SubName2 ID Sub-SubName3
ID RootName2 ID SubName1 ID Sub-SubName1
ID RootName2 ID SubName2
ID RootName2 ID SubName3

The ID would be of each root and node/subnode etc

I think I’ve got this working – i was just wondering if this is the ‘correct’ way of doing this or if this a better way. This is being done against an MS SQL 2012 express db.

select c.id, 
       c.name, 
       c1.Name, 
       cr1.CategoryID, 
       c2.Name, 
       cr2.CategoryID 
from Category c
left outer join CategoryRelationship cr1 on cr1.CategoryParentID = c.id
left outer join CategoryRelationship cr2 on cr2.CategoryParentID = cr1.CategoryID
inner join Category c1 on c1.ID = cr1.CategoryID
inner join Category c2 on c2.id = cr2.CategoryID
where c.CategoryTypeID = 1
order by c.name, c1.name, c2.name

There’s one more bit to this I need a little help with. There’s a 3rd table that has products in it. Each product has a SubCateoryID which would match up to cr2.CategoryID above. I would like to display the total number of items in the Product table for each cr2 category and i still want to include any categories that have no items in the product table. I’m not sure how to do that last part.

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1 Answer

  1. Editorial Team

    I think I have this:

    select c.ID, c.Name, c1.Name, cr1.CategoryID, c2.Name, cr2.CategoryID, 
(select count(*) from Product where product.SubcategoryID = cr2.CategoryID and Deleted = 0 and StatusID = 1) 
from Category c
left outer join CategoryRelationship cr1 on cr1.CategoryParentID = c.id
left outer join CategoryRelationship cr2 on cr2.CategoryParentID = cr1.CategoryID
inner join Category c1 on c1.ID = cr1.CategoryID
inner join Category c2 on c2.id = cr2.CategoryID
where c.CategoryTypeID = 1
order by c.name, c1.name, c2.name
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