how to merge many cell to one cell with keeping all data
 

Dear all,

I meet a question about following.
in A column, there are many data(some data are same), and in B column,
there are many relevant data, but they are different, how to merge all
the revelant data to one cell in B column with the same in A column,
thanks in advance!

For example

A B
123 R1
123 R2
123 R3
123 R4
124 L1
124 L2
124 L3
125 C1
125 C2
. .
. .
. .


BR
Valley