Is there a "period" column in your each dataset ? If there is no, then you must create one from the dataset name, before joining all datasets. If you dont do this you cannot compare data each other. Because all of them mixes. If you dont want to understand complex issues or if you do this work for one time, you can create libname statements in excel and then paste it to sas. Then join all and use proc sql drop table statement... Or if there is awant batch work or automatically process i used to write a macro which contains do-loop.and compare and export result.
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