Let's notice a few more points in the basic JOIN query.
Notice that the number of students is 25 in the students table. The number of
records in the result of JOIN query is only 22. Here are the reasons.
These three students are not included in the final result of the JOIN query.
These kinds of joins are also called INNER JOIN. In INNER JOIN only those
rows are included which strictly match the criteria. The criteria for this query
is that the courseId of the student should match with the Id in the courses
table.
We can replace JOIN in the above query with INNER JOIN, and Note that the
results still remain the same.