Using measure to compare two columns in a matrix

[vsorensen]

As the title suggests, I have two columns in a matrix that I need to compare. Both are date columns and I am trying to display the difference between the two. The issue I'm having, is when I try to directly compare the two columns, the matrix is populated with every single row in my table. For example, this is the result I am looking for, where "Start" and "Baseline Start" are the columns I am pulling in from my data table, and "Start Variance" is a measure:

WBS	Start	Baseline Start	Start Variance
WBS1	3/1/2023	1/16/2023	-31
WBS2	3/1/2023	1/16/2023	-31
Work Package 2	3/1/2023	1/16/2023	-31
Work Package 5	6/3/2024	2/8/2024	-80
Work Package 6	2/1/2024	5/3/2024	65

But when I try and create a start variance measure like this:

Start Variance = 
IF([Start] = [BL Start], 0, NETWORKDAYS([Start], [BL Start]))

Then I end up with a matrix that lists every single row in my data table, which is what I do not want:

WBS	Start	Baseline Start	Start Variance
WBS1	3/1/2023	1/16/2023	-31
WBS2	3/1/2023	1/16/2023	-31
Work Package 1			0
Work Package 2	3/1/2023	1/16/2023	-31
Work Package 3			0
Work Package 4			0
Work Package 5	6/3/2024	2/8/2024	-80
Work Package 6	2/1/2024	5/3/2024	65

So how do I create a measure that compares these two columns?

[Greg_Deckler · Accepted solution]

@vsorensen Try:

Start Variance = 
  SWITCH( TRUE(),
    [Start] = BLANK(), BLANK(),
    [Start] = [BL Start], 0, 
    NETWORKDAYS([Start], [BL Start])
  )

[vsorensen]

@Greg_Deckler I had to put MIN() around my column references but other than that it worked, thank you! Can you explain why this works? I had tried the code below before in one of my many attempts to figure it out but with no luck. 

SWITCH(
   TRUE(),
   MIN([Start]) = MIN([BL Start]), 0,
   ISBLANK(MIN(p6_data[BL Start])), BLANK(),
   NETWORKDAYS([Start], [BL Start])
)

[Greg_Deckler]

@vsorensen Oh, fair, I guess it is a measure and all. Basically, SWITCH TRUE is a nifty way of writing nested IF statements more cleanly. So, with SWITCH TRUE, you list out logical tests which are evaluated in order. If a logical test is met, then the corresponding value is returned so think of it like this:

SWITCH( TRUE(), 

  <Logical Test 1>, <Result if Logical Test 1 is true>,

  <Logical Test 2>, <Result if Logical Test 2 is true>,

  <Result if all other tests evaluate to false>

[vsorensen]

@Greg_Deckler right, I am familiar with the SWITCH TRUE formula, my question is if you had any insight as to why the SWITCH formula in my last message did not work while the one you provided did. From what I can tell, the two are effectively the same.