MySQL query to select average from distinct column of table?

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)