merging data frames

Hi,

I have been struggling with the issue of merging data frames that have
common columns and have different dimensions. Although I made alot of
search about it on internet, I could not find any function that would
efficiently perform the required operation. So I would appreciate if anyone
knowing how to resolve the problem would explain me the solution.

As you will see, the below data frames have one common column (they would
have multiple common columns in general), and I simply want to create a
table that is the union of A and B, say table C. So the first row of C must
include all the necessary info about the person with the respective COMPID,
which is provided in A and B.

A:
COMPID CLR_DOT CA_TYPE CA_YEAR DT_FNDNG DT_BIOP NORMAL  1030956 XXGRX P 10
19890919 19890919 0  2511425 XXXRX T 6 19891005 19891030 0  3205129 XXGRX T
8 19900227 19900227 0 ...

B:
COMPID CNTR_ALL ALLOC AG_GRCAL ENRL_DT EXP_SCR  1000012 0 NO 1 19800122 5
1000021 0 NO 2 19800121 5  1000030 0 NO 3 19800121 5  1000049 0 NO 4
19800121 5 ...

I tried rbind.fill but it did not work. I am aware that such operations can
be done in SAS in a minute, so I thought R should be as efficient as SAS in
performing such operations...

Thank you in advance,

Yasin

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