SQL Query From two Table satisfying a condition - mysql

Question

Table 1 name: Student
Name Department
Alex CSE
Bob EEE
Briyan ME
John CSE
James ETE
Mike CE
Table 2 name: Program
Department Semester
CSE Summer
CSE Winter
EEE Summer
ETE Summer
ME Winter
CE Summer
CE Winter
What is the SQL query to print the names and the semester where each student's department have only 1 type of semester? (the server is mysql)
SQL Query Result should be like this:
Name Semester
Bob Summer
Briyan Winter
James Summer
Here, CSE and CE have both summer and winter semester. So Alex, John and Mike are not included.
I have tried this far:
SELECT Student.Name,
Program.Semester
FROM Student
JOIN Program
ON Program.Department = Student.Department
WHERE ....

Answer 1

You could use a In clause on a subquery whetre coubt the department with only a entry
select a.Name, b.Departmnet
from Student a
inner join program b on a.Department = b.Department and b.Department In (
select Department from Program
group by Department having count(*)=1
)

Answer 2

CREATE TABLE #Student(Name NVARCHAR(50),Department NVARCHAR(50))
CREATE TABLE #Program (Department NVARCHAR(50),Semester NVARCHAR(50))
INSERT INTO #Student
SELECT 'Alex','CSE' UNION ALL
SELECT 'Bob','EEE' UNION ALL
SELECT 'Briyan','ME' UNION ALL
SELECT 'John','CSE' UNION ALL
SELECT 'James','ETE' UNION ALL
SELECT 'Mike','CE'
INSERT INTO #Program
SELECT 'CSE','Summer' UNION ALL
SELECT 'CSE','Winter' UNION ALL
SELECT 'EEE','Summer'UNION ALL
SELECT 'ETE','Summer'UNION ALL
SELECT 'ME','Winter'UNION ALL
SELECT 'CE','Summer'UNION ALL
SELECT 'CE','Winter'
;WITH CTE AS (
SELECT Name ,MAX(b.Semester)semester
FROM #Student a INNER JOIN #Program b ON a.Department=b.Department
group by name
having count(distinct semester) = 1
)
SELECT * FROM CTE
GO

Answer 3

You want to join students with single-semester departments. So aggregate your program data by semester to get the single-semester departments. As there is exactly one semester for these departments, you can get the semester with any_value(semester).
select s.name, d.the_semester
from student s
join
(
select any_value(semester) as the_semester
from program
group by department
having count(*) = 1
) d on d.department = s.department
order by s.name;
Another way would be to get all student semester combinations and the group by student to keep only single-semester students.
select s.name, any_value(p.semester) as the_semester
from student s
join program p on p.department = s.department
group by s.name
having count(*) = 1
order by s.name;
Choose whichever query you like better.

Answer 4

You can use aggregation and filter in having clause for those names which have only one semester:
select s.name,
max(p.semester) as semester
from student s
join program p
on s.department = p.department
group by s.name
having count(distinct p.semester) = 1;