Fill in blank values from another column

[Eugenio211]

Hello, hope everyone is doing ok. I just wanted to ask help with a job that i'm doing.  I wanted to replace blank values with values from another column.

data have

Product A	Product B
S
S
L	L
M
S	S
L
M
M
M	M
L
L
L	L

wanted to have the below result:

Product A	Product B
S	S
S	S
L	L
M	M
S	S
L	L
M	M
M	M
M	M
L	L
L	L
L	L

Thanks a lot!

[PaigeMiller · Accepted solution]

In a data step

if missing(productb) then productb=producta;

[Eugenio211]

Thank you for the quick response.