proc sql 中的引号无论写的单的还是双的，warning均显示：没有解析宏_1 & _2.

请各位老师帮忙讲解一下：proc sql中的错误，谢谢！

data aa;
input m_1 m_2 n_1 n_2 x_1 x_2;
cards;
1 2 7 2 3 4
3 4 8 3 4 5
1 3 5 5 6 7
;
proc contents data=aa out=bb(keep=name);
run;

proc sql;
select name into:names_1 separated by " "from bb where name like"%_1";
select name into:names_2 separated by " "from bb where name like"%_2";
quit;

data names_1(keep=&names_1) names_2(keep=&names_2);
set aa;
run;