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robertpisarek's avatar
robertpisarek
Regular Visitor
8 years ago
Solved

Merge in Power Query based on conditions

How to merge the same table based on two conditions in PowerQuery?   For example in SQL:   select * from Table1 t1 inner join Table1 t2 on t1.TransactionID = t2.TransactionID and t1.CategoryID...
  • MarcelBeug's avatar
    MarcelBeug
    8 years ago

    My suggestion would be to join on TransactionID and remove the results where the CategoryID's are equal.
    As you require an inner join, this also means removing empty nested tables.

     

    let
        Source = Table.NestedJoin(Table1,{"TransactionID"},Table1,{"TransactionID"},"t2",JoinKind.Inner),
        FilteredOnCategory = Table.ReplaceValue(Source,each [t2],(Earlier) => Table.SelectRows(Earlier[t2],each [CategoryID] <> Earlier[CategoryID]), Replacer.ReplaceValue,{"t2"}),
        RestoredType = Value.ReplaceType(FilteredOnCategory,Value.Type(Source)),
        FilteredNoEmptyTables = Table.SelectRows(RestoredType, each not Table.IsEmpty([t2])),
        Expanded_t2 = Table.ExpandTableColumn(FilteredNoEmptyTables, "t2", {"CategoryID"}, {"t2.CategoryID"})
    in
        Expanded_t2

     

    The RestoredType step restores the column types from the Source table, as Table.ReplaceValues resets all column types to any.

Anonymous's avatar
Anonymous
Not applicable
8 years ago

MarcelBeug

 

I am familiar with EARLIER() in DAX. This is very interesing! 

 Earlier[t2] and the CategoryID  refer to [t2] table with nested Table1 but Earlier[CategoryID] looks at he Source[CategoryID]... -- this is where it's little confusing. So, we have  each [CategoryID] <> Earlier[CategoryID] . If Ealire[t2] is looking at nested table result, why wouldn't Earlier[CategoryID] look at nested result too, it has "ealier" prefix and it's logicly to amuse that. 

 

To put it in a different way, why Earlier[CategoryID] with prefix Earlier is not looking at nested tables (Earlier [t2]) but at the source?  

 

 

 

 

Thanks

MarcelBeug's avatar
MarcelBeug
Community Champion
8 years ago

An example at the Source step.

 

Earlier[CategoryID] is a column in Source.

Earlier[t2] is also a column in Source.

Earlier[Category] is not inside Earlier[t2].