help with calculated column

[bbbt123]

Hello, I need help with a calculated column.   I have a table, call it "Table1" with unique values per category, see example below:

category	value
a	30
b	40
c	50

Then I have another table, call it "Table2" like the one below:

week num	category	value
10	a	34
11	b	45
12	a	67
13	b	89

I have to create a new column in Table 2 where I add the corresponding value of Table 1 only once, only in the first row, not in each row. how can I achieve it in power bi?

[Greg_Deckler · Accepted solution]

I am thinking perhaps:

Column in Table2 = 
  VAR __Category = [category]
  VAR __MinWeek = MINX(FILTER(ALL('Table2'),[category]=__Category),[week num])
RETURN
  IF([week num] = __MinWeek,LOOKUPVALUE('Table1'[value],'Table1'[category],__Category),BLANK())

[amitchandak]

Create these two new columns in table 2

Count = countx(filter(table2,table2[category]=earlier(table2[category]) && table2[week num] <=earlier(table2[week num])),table2[week num])

from table 1 = maxx(filter(table1,table2[category]=(table1[category]) && table2[Count]=1),table1[value])

Appreciate your Kudos.