merge statement

[clq]

Does a merge statement need a by statement? If not, then when do we use a by statement with the merge statement? 

[SASKiwi]

Read the documentation first: https://documentation.sas.com/?docsetId=lestmtsref&docsetTarget=n1i8w2bwu1fn5kn1gpxj18xttbb0.htm&doc...

And if it is still not clear, then ask further questions. 

[Cynthia_sas]

Hi:
And in this previous forum posting: https://communities.sas.com/t5/SAS-Programming/Merge-datasets/td-p/463569 are some images and code to explain merge with BY.
Cynthia

[Reeza]

In addition, the documentation has a section that outlines the different way to combine data sets all side by side with code examples. 

http://support.sas.com/documentation/cdl/en/lrcon/65287/HTML/default/viewer.htm#n1xc1y8c37apw7n1erbi...

It's definitely worth a read.