最简单的方法是在 merge 语句中使用 keep 选项.

The simplest way is to use the keep option on your merge statement.

data result;
    merge table_1 (in=a) table_2 (in=b keep=id definition);
    by id;
    if a;
 run;

另一种意味着您不必对数据集进行排序的方法是使用 proc sql.

An alternative that means you don't have to sort your datasets is to use proc sql.

proc sql;
    create table result as
    select a.*,
           b.definition
    from table_1 a
    left join table_2 b on a.id = b.id;
quit;

最后，如果 table_2 很小，还有哈希表选项:

Finally, there is the hash table option if table_2 is small:

data result;
    if _n_ = 1 then do;
        declare hash b(dataset:'table_2');
        b.definekey('id');
        b.definedata('definition');
        b.definedone();
        call missing(definition);
    end;
    set table_1;
    b.find();
run;