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Posted 03-09-2016 11:04 PM
(19616 views)
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
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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
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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.
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Here is a nice pictorial of SQL joins: