Sum total of several MySQL columns stored in another column?

Question

I have several columns in a MySQL database that I would like to add and store in another column:

column1     column2     column3    subtotal
10          10           


        

Answer 1

How about this?

UPDATE tableName SET subtotal = (column1 + column2 + column3)

Update 1

If you really don't need subtotal column in table just use query as

SELECT *, (column1 + column2 + column3) as subtotal
FROM tableName

Demo