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wer61537
Calcite | Level 5

I wonder if a full outer join in proc sql is the equivalent of a merge using if (A or B).  

 

DATA All;
MERGE West(IN=A)
East(IN=B);
BY Id;
IF A OR B;
RUN;

3 REPLIES 3
Reeza
Super User

Depends on if you have multiple instances of your BY variables. 

There's several good write ups on data step vs sql joins - search on lexjansen.com

http://www2.sas.com/proceedings/sugi30/249-30.pdf

Kurt_Bremser
Super User

SQL will give you the cartesian product, while the data step will give you as many records for a given by value as were present in one of the input datasets.

example:

dataset a has 2 records for x = 1, while dataset b has 3.

SQL (join on a.x = b.x) will give you six records (all combinations), the data step merge (by x; with if a or b;) 3.

 

RW9
Diamond | Level 26 RW9
Diamond | Level 26

Here is a nice pictorial of SQL joins:

Capture.PNG

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