为了便于讨论，假设您更改了宏变量的名称 M 更可笑的表达，例如 YN_OPTION_SELECT_M_STATES ```
%let YN_OPTION_SELECT_M_STATES = N;

proc sql;
select states,profit,
case
when .....
else
end
from geography_dim

/* add this */
where
("&YN_OPTION_SELECT_M_STATES" eq 'N' & STATE not like 'M%')
or
("&YN_OPTION_SELECT_M_STATES" ne 'N' & STATE like 'M%')

;
quit;

还原为宏变量 `M` 但是，如果必须这样做，代码将有点不透明。

它不是sql，但在datastep中非常简单。如果您想用m宏值检查起始值，在这种情况下为“n”，您可以这样做：

/*test data*/
    data geography_dim ;
    states="Aaaaa";profit=10;output;
    states="Naaaa";profit=10;output;
    run;
    /*set macro variable*/
    %let M=N;
    /*check if you want*/
    %put "&M";
    /*your case in datastep*/
    data test;
     set geography_dim;
     if substr(states,1,1) eq "&M" then profit=profit*10;
     else profit=0;
    run;
    /* results
    states  profit
    Aaaaa   0
    Naaaa   100
    */