请问sas的sql中有没有记录行观测号的变量呢？比如我想从第3行开始select……应该怎么实现？谢谢！

proc sql noprint;
select cat("mean(",compress(name),") as  ",compress(name),"_mean")
into: mean_names        separated by ","
from dictionary.columns
where libname="SASHELP" and memname="CLASS";
quit;
%put &mean_names;