Find observations that contain one word but NOT another

[shughe5]

I am trying to find observations that contain one word in a string but NOT another.

For example, my observations look something like this:

Diabetes mellitus

Screening for diabetes mellitus

Type II diabetes 

History of diabetes

Family history of type II diabetes

Encounter for screening of diabetes mellitus

I want to return observations that contain 'diabetes' or 'Diabetes' but NOT 'Screening' 'screening' 'History' 'history'

I tried what I thought the most intuitive way to do this would be:

proc freq data=data;

tables diagnosis;

where find(diagnosis, 'diabetes') or find(diagnosis, 'Diabetes') and not find(diagnosis, 'History') or find(diagnosis, 'screening');

run;

but obviously, this did not work and returned observations that DO contain History and Screening, ignoring the 'not.' Is the find function the best way to do this? 

[PaigeMiller · Accepted solution]

data want;
    set have;
    if find(diagnosis,'diabetes','i')>0 and find(diagnosis,'history','i')=0 and find(diagnosis,'screening','i')=0;
run;

[shughe5]

Awesome, thank you.