How to Create A Dynamic List from a String Column

[Tobz007]

I have a table (lets call it "Table") that contains "Names", "Date" and other info for the Names, every month a new list is appended to the Table to show the names and updated information, sometimes the appended table contains same name from last month, sometimes it contains some new names and sometimes some names from previous month is removed, how do I create power query steps (or DAX) that;
1. Creates a list which comprises of the names from the previous month in the Table.
2. Based on the list, if a name from the previous month list no longer exist in current month, it returns A, if name that does not exist in previous month is added in current month it returns B, else C.

[v-tangjie-msft · Accepted solution]

Hi @Tobz007 ,

Thanks to mickey64  and ryan_mayu  for their quick replies. I have a DAX method to add:

(1) This is my table. It contains data for this month and last month.

(2) We can create a [Previous month] table.

Previous month = 
var _month=MONTH(MAXX(ALL('Table'),[Date]))-1
RETURN CALCULATETABLE(VALUES('Table'[Name]),FILTER('Table',MONTH([Date])=_month))

(3) We can create a table and a status column.

Table 2 = VALUES('Table'[Name])

Status = 
var _month=MONTH(MAXX(ALL('Table'),[Date]))
var _table= CALCULATETABLE(VALUES('Table'[Name]),FILTER('Table',MONTH([Date])=_month))
var _table_a=EXCEPT('Previous month',_table)
var _table_b=EXCEPT(_table,'Previous month')
RETURN SWITCH(TRUE(),
[Name] in _table_a,"A",
[Name] in _table_b,"B",
"C")

Best Regards,

Neeko Tang

If this post  helps, then please consider Accept it as the solution  to help the other members find it more quickly. 

[Tobz007]

Thanks alot v-tangjie-msft, I did found a way around the solution using power query, but your feedback is quite helpful! Thanks again.

[mickey64]

Step 0: I use these data.

"PreviousMonth" Table

"ThisMonth" Table

Step 1: I do "Merge Queries as New" to "PreviousMonth" Table on Power Query Editor.

Step 2: I add a "Conditional" column below.

Step 3: I remove the "ThisMonth.Names" column and change a type of "Custom" column to "Text".

Step 4: I do same procedure to "ThisMonth" Table.

Step 5: I do "Append Queries as New" to the "Merge1" Table and the "Merge2" Table.

Step 6: I remove duplicates.

Step 6: I make a table.

[Tobz007]

Thanks alot mickey64, really appreciate the reply.

[ryan_mayu]

could you pls provide some sample data and expected output?