Averaging a total from a Score column in MySQL with the count of distinct ids?

You can use DISTINCT along with COUNT(). Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Id int,
   -> Score int
   -> );
Query OK, 0 rows affected (0.95 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(10,90);
Query OK, 1 row affected (0.16 sec)

mysql> insert into DemoTable values(10,190);
Query OK, 1 row affected (0.16 sec)

mysql> insert into DemoTable values(11,230);
Query OK, 1 row affected (0.18 sec)

mysql> insert into DemoTable values(11,130);
Query OK, 1 row affected (0.17 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+------+-------+
| Id   | Score |
+------+-------+
|   10 |    90 |
|   10 |   190 |
|   11 |   230 |
|   11 |   130 |
+------+-------+
4 rows in set (0.00 sec)

Here is the query for averaging a total from a Score column in MySQL with the count of distinct ids. The distinct ids are 2 here, therefore to find the average the total 640 i.e. 90 + 190 + 230 + 130 would be divided with 2 −

mysql> SELECT SUM(Score) / COUNT(DISTINCT Id) from DemoTable;

This will produce the following output −

+---------------------------------+
| SUM(Score) / COUNT(DISTINCT Id) |
+---------------------------------+
|                        320.0000 |
+---------------------------------+
1 row in set (0.00 sec)