tricky merging

[chriswong1386]

data test1;
input id $ marks1 ;
datalines;
a1 10
a2 20
a3 30
a4 40
a7 70
a8 80
a9 90
a10 100
;
data test2;
input id $ marks2;
datalines;
a1 10
a2 20
a3 30
a4 40
a5 50
a6 60
a7 70
a8 80
a9 90
a10 100
;

proc sort data=test1;
by id;
proc sort data=test2;
by id;

data merge1;
merge test1 test2;
by id;

the current result is the following 

1

a1

10

10

2

a10

100

100

3

a2

20

20

4

a3

30

30

5

a4

40

40

6

a5

.

50

7

a6

.

60

8

a7

70

70

9

a8

80

80

10

a9

90

90

But I just want to show the output contain in test two but missing in test one by id

the following is the result I desire:

a5 50

a6 60

please help! I can't find similar examples in my lecture notes ,wanna cry

[chriswong1386]

need to be done by a data set ,can not use proc sql

[mkeintz]

Look at

1. The  IN= Data Set Option  
   and
2. The  Subsetting IF statement.

[Tom · Accepted solution]

Do you want the observations that are not in TEST1?

data merge1;
  merge test1(in=in1) test2(in=in2);
  by id;
  if not in1;
run;

Or the observations that have a missing value for the variable MARKS1?

data merge1;
  merge test1(in=in1) test2(in=in2);
  by id;
  if missing(marks1);
run;

[AndreaVianello]

data test1;
input id $ marks1 ;
datalines;
a1 10
a2 20
a3 30
a4 40
a7 70
a8 80
a9 90
a10 100
;
data test2;
input id $ marks2;
datalines;
a1 10
a2 20
a3 30
a4 40
a5 50
a6 60
a7 70
a8 80
a9 90
a10 100
;
run;

proc sql;
create table want as
select test1.id, marks1, marks2
from test1 right join test2
on test1.id=test2.id
; quit;