Number of Unique Subjects Taught by Each Teacher

Table: Teacher

+-------------+------+
| Column Name | Type |
+-------------+------+
| teacher_id  | int  |
| subject_id  | int  |
| dept_id     | int  |
+-------------+------+
(subject_id, dept_id) is the primary key (combinations of columns with unique values) of this table.
Each row in this table indicates that the teacher with teacher_id teaches the subject subject_id in the department dept_id.

Write a solution to calculate the number of unique subjects each teacher teaches in the university.

Return the result table in any order.

The result format is shown in the following example.

LeetCode Problem - 2356

select teacher_id, count(distinct(subject_id)) as cnt 
from Teacher
group by teacher_id;