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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)
Updated on: 04-Oct-2019
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