How to merge Text/Character ?

[#1]

Dear Sir

I try find the related discussion before, but it seems not easy.

I would like ask how to  merge Char.A + Char.B in new column, thank you.

Char.A	Char.B	Merge
A	01	A.01
B	02	B.02
C	03	C.03
D	04	D.04
E	05	E.05
F	06	F.06
G	07	G.07

[#2]

Dear Sis

Let me describe again,

Merge1 is doable form formula (character --> concat)

Merge2  I wish to add new character (not in data table), like "_"  dash. how to reach this..

[#3 · Accepted solution]

:Char.A || "_" || :Char.B

[#4]

Thanks for quick answer