汇总mysql表中一行中的列值

Question

I am new to mysql. I am in need to sum the column values of he same row in table and update the summed value in the same table using mysql. Table name is Students

Name     roll_no    mark1      mark2     mark3      total    percentage
zxc      001         10          20        30         ?          ?
asd      002         20          30        50         ?          ?

I need mysql query to find total and percentage and update it in the corresponding columns. After doing this if I do SELECT * from Students . It has to display the following

Name     roll_no    mark1      mark2     mark3      total    percentage
zxc      001         10          20        30         60          60
asd      002         20          30        50         100         100

Answer 1

You need to add those col values for total value and for percentage if I am correct for each subject 100 marks and to value is devides by 300 here(for 3 subjects)

SELECT roll_no, mark1, mark2,mark3,   
mark1+mark2+mark3 as total,(mark1+mark2+mark3)*100/300 percentage
    From students

But as per your logic percentage is something like below

SELECT roll_no, mark1, mark2,mark3,   
    mark1+mark2+mark3 as total,(mark1+mark2+mark3)*100/100 percentage
        From students

But first one seems more meaningful than latter

As per OP comments, data should be updated in the columns

Update students set total=mark1+mark2+mark3, 
Percentage=(mark1+mark2+mark3)*100/300

Now select the table, you will get calculated total and percentage