Solved: Re: Evaluating in DAX Studio

Fcoatis · ‎07-11-2021

Hello all, need some help here. Here´s a sample data:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("bdG9CsMgFIbhe3EO5Pzp0Svo2j1kCDRb2kLvf6iNJhD6iYPwvMPhOE2BeKxXSDgM4fbeHs/lVV9M9YR5mIKOla9YDov/xsIdHaAqNywALRnvyAw0McWmYCJ2565opmI5NQVDCZtaUzCVaHTf9bKp+/pZt235BeemSHAgZ6A4MDkCw0FK0oOIgyJZWpBgoCJ98eQ4iKZt+ZRxkIu3LVGBgUn2/n2Eg/pFOczzFw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Data = _t, Banco = _t, Valor = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Data", type date}, {"Banco", type text}, {"Valor", Int64.Type}})
in
    #"Changed Type"

I´m trying to evaluate in DAX Studio:

EVALUATE
VAR _Passo1 =
    SUMMARIZE ( Trans, Trans[Banco], Trans[Data], Trans[Valor] )
VAR _Passo2 =
    ADDCOLUMNS (
        _Passo1,
        "@Dif",
            VAR _AtualBanco = Trans[Banco]
            VAR _AtualData = Trans[Data]
            VAR _AtualValor = Trans[Valor]
            VAR _DataM1 =
                FILTER ( _Passo1, Trans[Banco] = _AtualBanco && Trans[Data] < _AtualData )
            VAR _AntValor =
                MAXX ( _DataM1, Trans[Valor] )
            VAR _Dif =
                IF ( NOT ISBLANK ( _AntValor ), _AtualValor - _AntValor )
            RETURN
                _Dif
    )
RETURN
    _Passo2

Here is my result:

I know the difference (Column @Dif) is wrong because is computing the MAXX of the temporary table _DataM1. My question is: How can I get the last value Trans[Valor] of this temporary table? Please note that I need a solution in evaluation, cause I´m trying to understand querying in DAX Studio. I already created a measure in my model that is functioning. But I strictly need a evaluation statement in DAX Studio as a way of learning.

Thanks in advance.

parry2k · ‎07-11-2021

@Fcoatis try this expression:

EVALUATE
VAR _Passo1 =
    SUMMARIZE ( Query1, Query1[Banco], Query1[Data], Query1[Valor] )
VAR _Passo2 =
    ADDCOLUMNS (
        _Passo1,
        "@Dif",
            VAR _AtualBanco = Query1[Banco]
            VAR _AtualData = Query1[Data]
            VAR _AtualValor = Query1[Valor]
            VAR _DataM1 =
                FILTER ( _Passo1, Query1[Banco] = _AtualBanco && Query1[Data] < _AtualData )
            VAR _AntValor =
                CALCULATE ( MAX ( Query1[Valor] ), TOPN ( 1, _DataM1, [Data], DESC ) )
            VAR _Dif =
                IF ( NOT ISBLANK ( _AntValor ), _AtualValor - _AntValor )
            RETURN
                _Dif
    )
RETURN
    _Passo2

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View solution in original post

CNENFRNL · ‎07-11-2021

VAR _AntValor = MAXX ( TOPN( 1, _DataM1, Trans[Data] ), Trans[Valor] )

Thanks to the great efforts by MS engineers to simplify syntax of DAX! Most beginners are SUCCESSFULLY MISLED to think that they could easily master DAX; but it turns out that the intricacy of the most frequently used RANKX() is still way beyond their comprehension!

DAX is simple, but NOT EASY!