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MySQL query to find the average of rows with the same ID
Let us first create a table −
mysql> create table DemoTable ( StudentId int, StudentMarks int ); Query OK, 0 rows affected (0.83 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable values(1000,78); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(1001,88); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(1000,89); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(1000,67); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(1000,90); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(1001,91); 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 −
+-----------+--------------+ | StudentId | StudentMarks | +-----------+--------------+ | 1000 | 78 | | 1001 | 88 | | 1000 | 89 | | 1000 | 67 | | 1000 | 90 | | 1001 | 91 | +-----------+--------------+ 6 rows in set (0.00 sec)
Following is the query to find the average of rows with the same ID −
mysql> select StudentId,avg(StudentMarks) from DemoTable group by StudentId;
This will produce the following output −
+-----------+-------------------+ | StudentId | avg(StudentMarks) | +-----------+-------------------+ | 1000 | 81.0000 | | 1001 | 89.5000 | +-----------+-------------------+ 2 rows in set (0.03 sec)
Updated on: 27-Sep-2019
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