DAX table joins

  • All,

    I'm trying to improve my understanding of cubes and DAX but I'm missing something. If possible I would appreciate being pointed in the right direction.

    My model has two tables - Post and PostTypes.

    Post is the fact tables and PostTypes is a measure table.

    There is a link, within the model, between Post.PostTypes and PostTypes.ID

    My understanding is that because the link is in the model I don't need to specify the join in DAX queries?

    I'm using the following query:

    evaluate (


    I'm aiming for the equivalent of:

    select * from posts inner join posttypes on posts.posttype=posttypes.id where posttypes.id=1

    I get the error:

    Query (3, 14) A single value for column 'id' in table 'posttypes' cannot be determined. This can happen when a measure formula refers to a column that contains many values without specifying an aggregation such as min, max, count, or sum to get a single result.

    It looks like the DAX query is trying to establish a single value in posts.posttype instead of doing the join and using the posttypes.id column which does have single values? However I don't know why?



  • Thanks for posting your issue and hopefully someone will answer soon.

    This is an automated bump to increase visibility of your question.

  • I think I partially figured this out? My understanding is as follows?:

    Some functions in DAX use 'row context' and some use 'filter context'.

    A function using 'row context' can't join tables automatically.

    A function using 'filter context' can join tables automatically.

    The below code solved the issue in my first post:

    evaluate (



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