two WHERE statements in a data step

[mlm155]

I tried a data step with two where statements and realised that only the second where condition is affecting the output - see sample code below:

data result_2where_conditions;
set class_birthdate;
where Registration = 'C';

where Age = 12;

run;

Can somebody shed some light on why this happens?

Thanks heaps.

[Kurt_Bremser · Accepted solution]

Only one WHERE statement can take effect, the second overrides the first. Combine both conditions in one statement with AND.

[Astounding]

Alternatively, add the keyword SAME to the second WHERE statement:

where same and age=12;

[Kurt_Bremser]

While this is valid and works, I would not even teach it, as sooner or later someone comes up with

where condition1;
/* 1000 lines of data step code */
where same and condition2;
/* another 1000 lines of data step code */
where same and condition3;

which is horrible to debug and maintain.

[Astounding]

I agree, for simple sets of conditions. For complex sets of conditions, it can be easier to read the "same and" version.