Anybody have some good resources on using select distinct vs group by? I feel hesitant when using them and find myself confused as to which one to use or if there are times you need to use both.
Thanks!
Paul
Run below and examine the results. May be that explains things to you already a bit more.
In a nutshell: You use DISTINCT to de-duplicate rows, you use GROUP BY to aggregate values by the variables in the group by statement.
data have;
input groupvar nvar cvar $;
datalines;
1 10 A
1 10 A
1 20 B
2 50 B
2 40 B
;
run;
proc sql;
select distinct groupvar, nvar, cvar
from have
;
select groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
;
select distinct groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
;
select distinct groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
having sum(nvar)>80
;
quit;
Run below and examine the results. May be that explains things to you already a bit more.
In a nutshell: You use DISTINCT to de-duplicate rows, you use GROUP BY to aggregate values by the variables in the group by statement.
data have;
input groupvar nvar cvar $;
datalines;
1 10 A
1 10 A
1 20 B
2 50 B
2 40 B
;
run;
proc sql;
select distinct groupvar, nvar, cvar
from have
;
select groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
;
select distinct groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
;
select distinct groupvar, sum(nvar) as sum_nvar, cvar
from have
group by groupvar
having sum(nvar)>80
;
quit;
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