Finding average marks of students for different subjects and display only the highest average marks in MySQL
For this, you can use subquery. Let us first create a table −
mysql> create table DemoTable
(
StudentName varchar(40),
StudentMarks int
);
Query OK, 0 rows affected (0.50 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values('Adam',56);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('Chris',78);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('Adam',89);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('Robert',98);
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values('Chris',65);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('Robert',34);
Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+-------------+--------------+
| StudentName | StudentMarks |
+-------------+--------------+
| Adam | 56 |
| Chris | 78 |
| Adam | 89 |
| Robert | 98 |
| Chris | 65 |
| Robert | 34 |
+-------------+--------------+
6 rows in set (0.00 sec)
Following is the query to find average marks of students and display only the highest average marks −
mysql> select max(avSal.StudentMarks)
from (select avg(StudentMarks) as `StudentMarks` from DemoTable group by StudentName) as avSal;
This will produce the following output −
+-------------------------+
| max(avSal.StudentMarks) |
+-------------------------+
| 72.5000 |
+-------------------------+
1 row in set (0.09 sec)
Published on 04-Oct-2019 10:00:55
