•说法一：
procsql;• createtable m13 as

• selectavg(csp)as avglev,

• count(stock)   asnobs,

• ind,year

• from m12 groupby ind,year;•quit;

••说法二：

•/*计算各行业的观测值数目em.regtj*/

•create table em.regtjas select distinct ind,year,

•n(stkcd)as nn

•from em.idxgroup by ind,year;