Change a cell without create a new colunm

Hi Mendes094,

There are several options available, but using "Replace Values" is likely the most intuitive choice.

let
    Source = Table.FromRecords(
        {
            [Type = "A", Value = 10],
            [Type = "B", Value = 20],
            [Type = "C", Value = 40],
            [Type = "D", Value = 50]
        },  type table [Type=text, Value=number]
    ),
    ReplaceValue = Table.ReplaceValue(Source,each [Value],each if [Type]="B" then 0 else [Value],Replacer.ReplaceValue,{"Value"})
in
    ReplaceValue

I hope this is helpful

Hi Mendes094  ,
Thanks for reaching out to the Microsoft fabric community forum.
I would like to thank m_dekorte  for their suggestion
I have tried to reproduce their M query.
I have imported data from Excel and then used their suggested M query to get required output

let
    Source = Excel.Workbook(File.Contents("C:\Users\Downloads\elif_.xlsx"), null, true),
    Sheet1_Sheet = Source{[Item="Sheet1",Kind="Sheet"]}[Data],
    #"Promoted Headers" = Table.PromoteHeaders(Sheet1_Sheet, [PromoteAllScalars=true]),
    #"Changed Type" = Table.TransformColumnTypes(#"Promoted Headers",{{"Type", type text}, {"Value", Int64.Type}, {"Results", Int64.Type}}),
    #"ReplaceValue" = Table.ReplaceValue(#"Changed Type",each [Value],each if [Type]="B" then 0 else [Value],Replacer.ReplaceValue,{"Value"})
in
    #"ReplaceValue"

It has successfully got the desired output 


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Hi Mendes094, another solution:

Output

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTI0UIrViVZyAjKNIExnINMEwnQBMk2BzFgA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Type = _t, Value = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"Value", type number}}),
    ReplacedValue = Table.FromRecords(Table.TransformRows(ChangedType, each _ & (if [Type] = "B" then [Value = 0] else [])), Value.Type(Table.FirstN(ChangedType, 0)))
in
    ReplacedValue

Hi Mendes094 ,

May I ask if you have resolved this issue? If so, please mark the helpful reply and accept it as the solution. This will be helpful for other community members who have similar problems to solve it faster.

Thanks and Regards

Hi Mendes094 ,

I wanted to check if you had the opportunity to review the information provided. Please feel free to contact us if you have any further questions. If the responses has addressed your query, please accept it as a solution and give a 'Kudos' so other members can easily find it.
Thank you

Hi Mendes094 ,

As we haven’t heard back from you, we wanted to kindly follow up to check if the solution provided by the community members for the issue worked. If our response addressed, please mark it as Accept as solution and click Yes if you found it helpful.

Thanks ands regards