Excel formula to extract unique values between two columns?

[MEUserII]

Consider the following data set:

​

R/C​	A​	B​	C​	D​
1​	A​	B​	​	A​
2​	C​	C​	​	B​
3​	C​	D​	​	C​
4​	D​	D​	​	D​
5​	D​	E​	​	E​
6​	F​	G​	​	F​
7​	G​	G​	​	G​
8​	G​	G​	​	H​
9​	G​	G​	​	​
10​	H​	H​	​	​
11​	H​	H​	​	​
12​	H​	H​	​	​
13​	H​	H​	​	​

​

Is there a way via an Excel formula to extract all unique values between two columns: column A and column B? Specifically, I have listed the desired result in column D.
For context, I am trying to come up with a formula that does this without using the new UNIQUE() function.

As a reference, there is an example formula linked below that provides a formula for how to extract unique values for only one column.
Link: Excel formula: Extract unique items from a list | Exceljet

 

[LouisT]

why do you want a formula to pull out "Unique" values without using the "unique" formula?

 

[MEUserII]

why do you want a formula to pull out "Unique" values without using the "unique" formula?

Thanks for the reply; I need this formula to be backwards compatible with some older versions of Excel that predate the addition of the UNIQUE() function. Any formula suggestions would be appreciated, thanks!

 

[Peter_SSs]

Not relevant to this question but in any case I suggest that you update your Account details (or click your user name at the top right of the forum) so helpers always know what Excel version(s) & platform(s) you are using as the best solution often varies by version. (Don’t forget to scroll down & ‘Save’)

I need this formula to be backwards compatible with some older versions

Try this

22 09 04.xlsm
	A	B	C	D
1
2	A	B		A
3	C	C		B
4	C	D		C
5	D	D		D
6	D	E		E
7	F	G		F
8	G	G		G
9	G	G		H
10	G	G
11	H	H
12	H	H
13	H	H
Unique

Cell Formulas
Range	Formula
D2:D13	D2	=IFERROR(INDIRECT(TEXT(AGGREGATE(15,6,(ROW(A$2:B$13)*10^6+COLUMN(A$2:B$13))/((A$2:B$13<>"")*(ISNA(MATCH(A$2:B$13,D$1:D1,0)))),1),"R000000C000000"),0),"")

 

[MEUserII]

Not relevant to this question but in any case I suggest that you update your Account details (or click your user name at the top right of the forum) so helpers always know what Excel version(s) & platform(s) you are using as the best solution often varies by version. (Don’t forget to scroll down & ‘Save’)

Thanks @Peter_SSs for the tip! I've updated my account details with Excel version(s) & platforms I'm using.

Try this

22 09 04.xlsm
	A	B	C	D
1
2	A	B		A
3	C	C		B
4	C	D		C
5	D	D		D
6	D	E		E
7	F	G		F
8	G	G		G
9	G	G		H
10	G	G
11	H	H
12	H	H
13	H	H
Unique

Cell Formulas
Range	Formula
D2:D13	D2	=IFERROR(INDIRECT(TEXT(AGGREGATE(15,6,(ROW(A$2:B$13)*10^6+COLUMN(A$2:B$13))/((A$2:B$13<>"")*(ISNA(MATCH(A$2:B$13,D$1:D1,0)))),1),"R000000C000000"),0),"")

Ah, this is an really clever solution @Peter_SSs. I'm going through the formula's calculation step by step to understand how to it works; specifically, this formula returns the desired result in $D$2 (seemingly in alphabetical order no less).
I've marked your post as the solution to this Excel problem; though I will likely follow up with a specific question on how this formula works.
For reference, I have a formula textbook, Control+Shift+Enter Mastering Excel Array Formulas by Mike "excelisfun" Girvin, and I was surprised a formula for this Excel problem wasn't in there.

 

[Peter_SSs]

(seemingly in alphabetical order no less)

That is only because the sample data was in alphabetical order.

22 09 04.xlsm
	A	B	C	D
1
2	J	X		J
3	K	C		X
4	C	D		K
5	D	D		C
6	D	E		D
7	F	G		E
8	G	A		F
9	G	G		G
10	G	G		A
11	H	H		H
12	H	H
13	H	H
Unique (3)

Cell Formulas
Range	Formula
D2:D13	D2	=IFERROR(INDIRECT(TEXT(AGGREGATE(15,6,(ROW(A$2:B$13)*10^6+COLUMN(A$2:B$13))/((A$2:B$13<>"")*(ISNA(MATCH(A$2:B$13,D$1:D1,0)))),1),"R000000C000000"),0),"")