I met a strange issue when I merge two datasets. Below is a simple example
data a;
subjid="101-001";
do visit='vis01', 'vis02';
do param="aaa", 'bbb', 'ccc';
output;
end;
end;
run;
data b;
subjid="101-001";
do visit='vis01', 'vis02';
flag="Y";
output;
end;
run;
proc sort data=b; by subjid visit; run;
proc sort data=a; by subjid visit; run;
data c;
merge a b;
by subjid visit;
if param='aaa' then call missing(flag);
/* if visit='vis01' then call missing(flag);*/
run;
I merged a and b. I hope only when param='aaa' then flag= missing. but if I run above code, all flag values are missing. I know if I do two data steps, I can resolve this issue. But I am not sure why this happened, and how I can avoild this issue. Please help me out. Thanks
George
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