Calculating and storing SUM of a column in another table
Some time we have to collect the SUM , AVG or any other type of data from one table and store them in another table. Say for example we want to store sum of all marks of each student in a different table. We conducted different exams for students and now we will be adding all the marks for each student and store them in a different table. We will be using GROUP BY command to find out sum of all the marks or each student. Here is the SQL to do this.
insert into student3_total(s_id,mark) select id, sum(math + social +science) from student3 group by id
The above query will total all marks of each student and then store them in s_marks table. You can use AVG, MAX,MIN commands in place of SUM command to get desire result. Here is the one for AVG marks
insert into student3_total(s_id,mark) select id, AVG(math + social +science) from student3 group by id
Creating a table & storing data.
If we have not created student3_total table before, then also we can create the table and store the data by using single query.
create table student3_total select id, AVG(math + social +science) from student3 group by id
Displaying the result with total mark using two tables
Above query will insert student id and sum of the mark to our student3_total table. Now we can join both table and display the final report. This report will collect name, id and individual mark from student3 table and total mark and student id from student3_total table.
Two tables are joined by student id of both tables . Here is the query
SELECT id, name, class, social, science, math, s_id, mark
FROM `student3` , student3_total
WHERE id = s_id
Here are our both tables with records for you to test the quey.
student3: Download the SQL dump of the above student table
student3_total : Download the SQL dump of total of student mark
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