Need help on function VLOOKUP

[NickProp28]

Dear Community,

I would like to create a new column to sum up the total weight from another table. But I dont want the total value are copying to every single row in my new table. I just want to show the value in only one of the ID.

My expectation: 
Table 1 

New table (vlookup) - Based on the ID

Thank for your attention. Any help will greatly appreciated.

[Greg_Deckler]

@NickProp28 You can use LOOKUPVALUE or MAXX(FILTER(...),...) for that.

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[NickProp28]

Dear @Greg_Deckler ,

I used LOOKUPVALUE, but result that it copying the result to every single row (based on ID) in my table. 
I only need the result show in only one of the record.
Kindly advice

[Greg_Deckler]

@NickProp28 So which record would that be? In other words how do you identify which row you want it in? 

[NickProp28]

Dear @Greg_Deckler ,

Any one of the row will be fine. 
If not doing that, at the end if I sum up the value for example C002, I will get 400 instead of 200.

[Greg_Deckler]

@NickProp28 That's not going to work. This is code. Code is not "hey pick a row, any row", there have to be rules so that the calculation knows when to return a number and when to return blank.

[NickProp28]

Dear @Greg_Deckler ,

How about I create another column to state the sequece number, so the calculation can return to first of the ID?

[Greg_Deckler]

@NickProp28 Bingo!

[NickProp28]

Dear @Greg_Deckler ,

Any hits on code could be provided? I lost on the SUM part and how does lookupvalue include the FILTER for num=1 in this case

Thank

[Greg_Deckler]

@NickProp28 Maybe:

Column = 
  VAR __ID = [ID]
RETURN
  IF([Num] <> 1),BLANK(),SUMX(FILTER('Table2',[ID]= __ID),[Weight]))

[NickProp28]

Dear @Greg_Deckler ,

Thanks for the feedback.
Following ur code but I encounter some issues. 

TABLEA's weight cant be put on this part 

[ryan_mayu · Accepted solution]

@NickProp28 

is this what you want? pls see the attachment below

[NickProp28]

Dear @ryan_mayu ,

Thanks!

[ryan_mayu]

you are welcome