Given the SAS data sets:
WORK.ONE WORK.TWO
Year Qtr Budget Year Qtr Sales
---------------------- --------------------
2001 3 500         2001 4 300
2001 4 400         2002 1 600
2003 1 350
The following SAS program is submitted:
proc sql;
select TWO.*, budget
from WORK.ONE
[_insert_join_operator_]
WORK.TWO
on ONE.Year=TWO.Year
;
quit;
The following output is desired:
Year Qtr Sales Budget
------------------------------
2001 4 300 500
2001 4 300 400
. . . 350
Which join operator completes the program and generates the desired output?
A. left join
B. right join
C. full join
D. outer join

我不明白为什么对于QTR中，没有“3”那个值，出来的只有“4”。能不能彻底解答下SELECT TWO里面拿出来YEAR, QTR,SALES三个变量from WORK.ONE究竟是什么？