proc sql;
create table c1 as
select year(c.year) as yr, c.COL1, c.region from c
;
select a.*, c.COL1
from a left join b on a.regn=b.region2
left join c1 on b.region1=c1.region and a.year=c.yr
;
quit;
应该是c1.yr。
proc sql;
create table c1 as
select year(c.year) as yr, c.COL1, c.region from c
;
select a.*, c.COL1
from a left join b on a.regn=b.region2
left join c1 on b.region1=c1.region and a.year=c1.yr
;
quit;