[Advanced Editor] Multiple if statement in M Script

[DominikW]

Hello everyone,

is it possible to create multiple if statement? I am asking here because I couldn't find any normal tutorial for this. If I use the code like this I am getting error "Token Identifier expected.", I am trying to create historical data for dataset for past 5 days. 

if 
    Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 0
then
    (let
        Source = Oracle.Database("LINK", [HierarchicalNavigation=true]),
        NAME = Source{[Schema="NAME"]}[Data],
        RENAME = NAME{[Name="DATASET"]}[Data],
        ConvertedPath = Text.Replace("PATHFORFILE", "\", "/"),
        RScript = R.Execute("write.csv(NAME,"""&ConvertedPath&""") 
                         output <- NAME
                         ",[NAME=NAME]),
        output = RScript{[Name="FILENAME"]}[Value]
    in
        output)
else
    (let
        Source = Csv.Document(File.Contents("PATHOFFILE.csv"),[Delimiter=",", Columns=, Encoding=, QuoteStyle=QuoteStyle.None]),
        #"Changed Type" = Table.TransformColumnTypes(Source,{COLUMNS}),
        #"Promoted Headers" = Table.PromoteHeaders(#"Changed Type", [PromoteAllScalars=true]),
        #"Changed Type1" = Table.TransformColumnTypes(#"Promoted Headers",{COLUMNS}),
/*IF AGAIN*/ 
if 
 Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 1
then
 (let
 Source = Oracle.Database("LINK", [HierarchicalNavigation=true]),
 NAME = Source{[Schema="NAME"]}[Data],
 RENAME = NAME{[Name="DATASET"]}[Data],
 ConvertedPath = Text.Replace("PATHFORFILE", "\", "/"),
 RScript = R.Execute("write.csv(NAME,"""&ConvertedPath&""") 
 output <- NAME
 ",[NAME=NAME]),
 output = RScript{[Name="FILENAME"]}[Value]
 in
 output)
else
 (let
 Source = Csv.Document(File.Contents("PATHOFFILE.csv"),[Delimiter=",", Columns=, Encoding=, QuoteStyle=QuoteStyle.None]),
 #"Changed Type" = Table.TransformColumnTypes(Source,{COLUMNS}),
 #"Promoted Headers" = Table.PromoteHeaders(#"Changed Type", [PromoteAllScalars=true]),
 #"Changed Type1" = Table.TransformColumnTypes(#"Promoted Headers",{COLUMNS}),
/*IF AGAIN*/ 

[MarcelBeug · Accepted solution]

Well, you can have multiple if statements as in the query below.

I included a "let .. in"  statement for Monday, just to illustrate how that would look like.

let
    Output = if Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 0
            then let InnerOutput = "Monday"
                  in InnerOutput
            else if Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 1
                then "Tuesday"
                else if Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 2
                    then "Wednesday"
                    else if Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 3
                        then "Thursday"
                        else if Date.DayOfWeek(DateTime.LocalNow(), Day.Monday) = 4
                            then "Thank God it's Friday"
                            else "Weekend!!"
in
    Output

In general the structure of a query is like:

let
    step1 = formula,
    step2 = formula,
    ...
    stepn = formula
in
    stepn

It is not possible to create an if ... then ... else statement without a step name.