What are the functions of the INNER JOIN and FULL JOIN in SQL?

The INNER JOIN in SQL returns records that have matching values in both tables, while FULL JOIN returns all records from both tables.

INNER JOIN is a type of join that fetches data if present in both the tables. If there is a match between the columns in Table A and Table B, then only the matched records will be displayed. It is the most common type of join in SQL. For example, if you have two tables, one for students and one for courses, and you want to find out which students are enrolled in which courses, you would use an INNER JOIN. This would return a list of students and the courses they are enrolled in, but only for students who are actually enrolled in a course. If a student is not enrolled in any course, they would not be included in the result.

FULL JOIN, on the other hand, is a type of join that fetches all records from Table A and Table B, regardless of whether there is a match between the columns. If there is no match, the missing side will contain null. Using the same example of students and courses, a FULL JOIN would return a list of all students and all courses. If a student is not enrolled in a course, they would still be included in the result, but the course information for that student would be null. Similarly, if a course does not have any students enrolled, it would still be included in the result, but the student information for that course would be null.

In summary, INNER JOIN and FULL JOIN are two types of joins in SQL that are used to combine rows from two or more tables based on a related column between them. The main difference between them is that INNER JOIN returns only the rows that have matching values in both tables, while FULL JOIN returns all rows from both tables, filling in null for missing matches on either side.