Sql SAS代码效率
有人可以帮助我了解SAS/SQL如何处理嵌套查询或子查询吗。它是只执行一次内部选择，“从主文件选择总和（价格）”还是每次迭代外部查询Sql SAS代码效率,sql,sas,Sql,Sas,有人可以帮助我了解SAS/SQL如何处理嵌套查询或子查询吗。它是只执行一次内部选择，“从主文件选择总和（价格）”还是每次迭代外部查询 proc sql; create table categorySpend as select categoryid, sum (price) as CategoryRevenue, (select sum(price) from MasterFile)as TotalRevenue from MasterFile group by categoryid;
proc sql;
create table categorySpend as
select categoryid, sum (price) as CategoryRevenue, (select sum(price) from MasterFile)as TotalRevenue
from MasterFile
group by categoryid;
quit;
了解幕后情况的最佳方法可能是在
proc sql\u方法和\u树
选项。对于非常详细的总结，这是一个很好的来源：