Compare Column(data) from different table and view in SQL Developer - sql

Question

I would like to compare few columns in different view with table.
For example:
View a:
student_id First_Name University high_degree
0011221 Tom New York university Y
0011221 Tom MIT N
0011222 Peter Harvard university Y
0011223 Sam Northeastern university Y
0011224 Leo Boston university Y
0011225 Paul Boston college Y (this is not correct)
0011225 Paul Tufts N
table b:
student_id First_Name University degree
0011221 Tom New York university MS
0011222 Peter Harvard university DR
0011223 Sam Northeastern university BS
0011224 Leo Boston university BS
0011225 Paul Tufts DR
Assume that the table b is the most update student information, but in the view a it is the old data from different old table and some student fill the wrong information, then I want to find out which students's information is incorrect.
For example Paul studied two school, Boston college for BS, Tufts for Doctor. In table B is the most update student info, Paul studied Tufts that is the high degree. However in view a Paul's high degree is Boston college so this is wrong information. I am looking for which student has same situation. how to do that?
Ideal result like:
student_id First_Name University high_degree result
0011221 Tom New York university Y match
0011221 Tom MIT N null
0011222 Peter Harvard university Y match
0011223 Sam Northeastern university Y match
0011224 Leo Boston university Y match
0011225 Paul Boston college N null
0011225 Paul Tufts Y not match
No need to same with ideal result, but just need to know which student in view a has different data by comparing with table b.
I appreciate your reply. thank you so much.

Answer 1

One option is to use outer join, while result is retrieved by case expression.
Sample data:
SQL> with
2 view_a (first_name, university, high_degree) as
3 (select 'Tom' , 'New York university', 'Y' from dual union all
4 select 'Tom' , 'MIT' , 'N' from dual union all
5 select 'Peter', 'Harvard university' , 'Y' from dual union all
6 select 'Paul' , 'Boston college' , 'Y' from dual union all
7 select 'Paul' , 'Tufts' , 'N' from dual
8 ),
9 table_b (first_name, university) as
10 (select 'Tom' , 'New York university' from dual union all
11 select 'Peter', 'Harvard university' from dual union all
12 select 'Paul' , 'Tufts' from dual
13 )
Query:
14 select a.first_name, a.university, a.high_degree,
15 case when a.university = b.university then
16 case when a.high_degree = 'Y' then 'Match'
17 when a.high_degree = 'N' then 'Not match'
18 end
19 else null
20 end result
21 from view_a a left join table_b b on a.first_name = b.first_name
22 and a.university = b.university
23 order by a.first_name desc, a.university;
FIRST UNIVERSITY HIGH_DEGREE RESULT
----- ------------------- ------------ ---------
Tom MIT N
Tom New York university Y Match
Peter Harvard university Y Match
Paul Boston college Y
Paul Tufts N Not match
SQL>