Merging Datasets not working, no observations

[SAS93]

I'm trying to merge 2 different datasets of different sizes (# OBS). They each share a common variable, but I had to rename & change one of them so their formats and variable names matched. >> I want to merge and keep only the obs that are found in the smaller dataset << I found a suggestion elsewhere to do the following in order to accomplish that: Data OrgList.match18a; Merge temp18 (IN = a) list18 (IN = b); By CommonVar; If a and b; Run; But NO obs are written to that new dataset; SAS is reading the other two datasets just fine and the renaming/reformatting is fine after I checked it. Without the "if a and b", the new dataset has a combined # of all obs from both datasets. What do I do to fix this?

[SAS93]

I don't know what happened to the formatting for this post. My apologies.

[SAS93 · Accepted solution]

Just kidding, I solved my own problem. 

One-to-one-merging worked. Not sure why the other method was even suggested to accomplish this. 

Data OrgList.match18a;
Set temp18;
Set hosp2018;
Run;