feat: add sql solution to lc problem: No.0580 (doocs#755)

No.0580.Count Student Number in Departments

Author: Dhoni77

solution/0500-0599/0580.Count Student Number in Departments/README.md

@@ -84,7 +84,14 @@ Department 表:
 ### **SQL**
 
 ```sql
-
+SELECT 
+    department.dept_name, COUNT(student.dept_id) student_number
+FROM
+    Student
+        RIGHT JOIN
+    Department ON student.dept_id = department.dept_id
+GROUP BY dept_name
+ORDER BY student_number DESC , dept_name;
 ```
 
 <!-- tabs:end -->

solution/0500-0599/0580.Count Student Number in Departments/README_EN.md

@@ -81,7 +81,14 @@ Department table:
 ### **SQL**
 
 ```sql
-
+SELECT 
+    department.dept_name, COUNT(student.dept_id) student_number
+FROM
+    Student
+        RIGHT JOIN
+    Department ON student.dept_id = department.dept_id
+GROUP BY dept_name
+ORDER BY student_number DESC , dept_name;
 ```
 
 <!-- tabs:end -->

solution/0500-0599/0580.Count Student Number in Departments/Solution.sql

@@ -0,0 +1,8 @@
+SELECT 
+    department.dept_name, COUNT(student.dept_id) student_number
+FROM
+    Student
+        RIGHT JOIN
+    Department ON student.dept_id = department.dept_id
+GROUP BY dept_name
+ORDER BY student_number DESC , dept_name;