MySQL query to select average from distinct column of table?

MySQLMySQLi Database

For getting average, use AVG() and use it with DISTINCT to calculate from distinct records. Let us first create a table −

mysql> create table DemoTable1934
   (
   StudentName varchar(20),
   StudentMarks int
   );
Query OK, 0 rows affected (0.00 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1934 values('Chris',56);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1934 values('Chris',56);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1934 values('David',78);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1934 values('David',78);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1934 values('Carol',45);
Query OK, 1 row affected (0.00 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1934;

This will produce the following output −

+-------------+--------------+
| StudentName | StudentMarks |
+-------------+--------------+
| Chris       |           56 |
| Chris       |           56 |
| David       |           78 |
| David       |           78 |
| Carol       |           45 |
+-------------+--------------+
5 rows in set (0.00 sec)

Here is the query to select average from distinct column of table −

mysql> select avg(tbl.StudentMarks)
   from
   (
   select distinct StudentName,StudentMarks
   from DemoTable1934
   ) as tbl;

This will produce the following output −

+-----------------------+
| avg(tbl.StudentMarks) |
+-----------------------+
|               59.6667 |
+-----------------------+
1 row in set (0.00 sec)
raja
Published on 30-Dec-2019 12:15:25
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