Hi,
I have two datasets A and B which I am trying to join and the scenario is a many to many join.
I am confused on the join. Does each record of dataset A gets the matching last record from B? Is it possible to have a control here so that each record in dataset A is combined with all the matching records from B
Any help will be greatly appreciated.
Thanks in advance
data A;
input code $ x y;
datalines;
AA 1 2
AA 3 4
AA 5 6
BB 7 8
CC 9 10
;
run;
data B;
input code $ z k;
datalines;
AA 10 20
AA 20 40
BB 70 80
BB 99 77
CC 90 100
;run;
Proc sort data = A;
By code;
Run;
Proc sort data = B;
By code;
Run;
Data c;
Merge A(in =ina) B;
If ina;
Run;
The ooutput i get is
The Actual output which I get is
AA 1 2 10 20
AA 3 4 20 40
AA 5 6 20 40
BB 7 8 70 80
BB 7 8 99 77
CC 9 10 90 100
Regards,
Sheeba Swaminathan
From the online help:
Note: The MERGE statement does not produce a Cartesian product on a many-to-many match-merge. Instead it performs a one-to-one merge while there are observations in the BY group in at least one data set. When all observations in the BY group have been read from one data set and there are still more observations in another data set, SAS performs a one-to-many merge until all observations have been read for the BY group.
So in your case for the Code=AA. First record of set a matched first of B, then second of A with second of B. B ran out of AA codes so remaing AA in set A matched against the last AA in dataset B.
Many to many joins are usually better left to Proc Sql.
From the online help:
Note: The MERGE statement does not produce a Cartesian product on a many-to-many match-merge. Instead it performs a one-to-one merge while there are observations in the BY group in at least one data set. When all observations in the BY group have been read from one data set and there are still more observations in another data set, SAS performs a one-to-many merge until all observations have been read for the BY group.
So in your case for the Code=AA. First record of set a matched first of B, then second of A with second of B. B ran out of AA codes so remaing AA in set A matched against the last AA in dataset B.
Many to many joins are usually better left to Proc Sql.
HI Ballardw,
Thanks a lot for the details.
Also i assume many to many merge differ from proc sql left join? is that correct.
Thanks again
Regards,
Sheeba Swaminathan
Hi LinusH,
Thank you.
Regards,
Sheeba Swaminathan
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