MySQL 8.0

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CREATE TABLE data1(
  student int,
  answer int
);
INSERT INTO data1(student, answer)
VALUES
(100, 1),
(100, 2),
(101, 1),
(101, 9),
(102, 1),
(102, 2),
(102, 2),
(103, 8),
(104, 2),
(104, 9);

Records: 10  Duplicates: 0  Warnings: 0


select student, if((sum(cnt)<>count(*)) or ((count(*)>1) and (max(answer)>7)), 'INVALID', 'Valid') as Result
from
(  
  select student, answer, count(*) as cnt
  from data1
  group by student, answer
) as sub
group by student


student
Result


100
Valid

101
INVALID

102
INVALID

103
Valid

104
INVALID