Description:
- Returns the average value of
_`expr`_. The DISTINCT option can be used to return the average of the distinct values of expr.
- If there are no matching rows,
AVG() returns NULL. The function also returns NULL if expr is NULL.
- This function executes as a window function if
over_clause is present. over_clause is as described in Section 12.20.2, “Window Function Concepts and Syntax”; it cannot be used with DISTINCT.
-
SELECT student_name, AVG(test_score)
FROM student
GROUP BY student_name;
```