How to query common values in Linq to SQL?
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Thread: How to query common values in Linq to SQL?

  1. #1
    Join Date
    Apr 2013
    Posts
    14

    Unhappy How to query common values in Linq to SQL?

    We have two tables PRODUCTS and CATEGORIES, both of them have a many-to-many relationship through a third table --> CATE_PRODUCTS

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    My question: given 1 or more ID_PRODUCT I need to retrieve all the COMMON Categories that belongs to those Products.

    Example: Given 3 Products IDs:

    PRODUCTS ---------- CATEGORIES of each one
    --------------------------------------------------------------
    COKE ------------> SelfService - Sale - **Beverage**
    ORANGE JUICE ----> **Beverage**
    VINE -------------> Licour - **Beverage**

    In this case 'Beverage' is the only one common category value for those 3 given Products

    I'm trying to do it through Linq To SQL in VB.NET, but not successful

    With the code below I retrieve all Categories from all given Products:

    Code:
    Dim Query = (From Cate In db.CATEGORIAS Join CatePro In db.CATE_PRODUCTOS
                         On Cate.ID_CATEGORIA Equals CatePro.ID_CATEGORIA
                        Where MiList.Contains(CatePro.ID_PRODUCTO) Select Cate.CAT_NOMBRE)
    But I need to retrieve ONLY the common Categories, not all Categories.

    żAny ideas?

    Thanks a lot !!!

  2. #2
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,998

    Re: How to query common values in Linq to SQL?

    Separate it into 2 different queries. Once the first one is done, use it against the second query. Look for 101 LINQ Samples on the Web


    Or Select.Unique? Might exist
    David

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  3. #3
    Join Date
    Apr 2013
    Posts
    14

    Re: How to query common values in Linq to SQL?

    Thanks dglienna !!!

    But it is hard to believe to me that this post has been viewed for about 92 persons and no body knows how to do this 'simple' SQL query or not want to.

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