May I know any ideas to compare the unique ID of 2 data set and
combine into one set.
the number of rows of Data A & B maybe up to 40000 rows. If loading to
array or row to row compare (if...then) maybe very slow...
I would like to seek for a quick method. Currently I used if/then
function, but need 5~10mins for combine...
Thank you very much in advance.

for example:
Data A
ID Column B
U1 20
U2 30
U3 40
U4 50


Data B
ID Column B
U4 0.2
U2 0.9
U1 9.9
U3 100

Result
ID Column B Column C
U1 20 9.9
U2 30 0.9
U3 40 100
U4 50 0.2