1.逻辑表达：>,<,!=,....
*data step;
data class_flags;
set sashelp.class;
tall = (height > 60);
male = (sex = 'M');
female = (sex = 'F');
run;
*proc sql;
proc sql;
select name,
(height > 60) as tall,
(sex = 'M') as male,
(sex = 'F') as female
from sashelp.class;
quit;
2.描述性统计函数sum(),mean(),....
proc sql;
select sex,
max(height) as max_ht,
mean(weight) as mean_wt
from sashelp.class
group by sex;
quit;
proc sql;
select age,
max(height*height/weight) as max_body_mass_index
from sashelp.class
group by age;
quit;
3.联合使用
proc sql;
select max(height > 60) as any_tall,
mean(weight > 100) as pct_heavy,
sum(gender = 'F') as num_female
from sashelp.class;
quit;
proc sql;
select sex,
max(height > 60) as any_tall, mean(weight > 100) as pct_heavy
from sashelp.class
group by sex;
quit;