Here is my situation:

Im trying to figure out how to add rows together to get "volume"

here an example of my table

id symbol shares volume price
13 JAME 100 100 50.00
14 JAME 50 "X" 50.00

what SQL query do i use to make the "x" in id 14 equal to the volume in 13 + shares in 14.

basically how do i have "X" replaced with 150

i do want the number to add up so i can have an idea of the volume of the shares. this needs to be updated so the price will fluctuate with it. Also im trying to figure how to make Y fluctuate based on "X"


id symbol shares volume price
13 JAME 100 100 50.00
14 JAME 50 "X" "Y"
15
16...

See if I have this right.

You want "volume" to be a running total of two values. Yes?

If so, it cannot be done in a single SQL query. SQL simply doesn't work like that.
At first looks I would say that you will need to write a stored procedure to perform a query that returned the required records, THEN have a routine to iterate through the returned rows and insert the running total into each row.
Certainly NOT something for an inexperienced DBA to be trying to accomplish

Your running total would be done simpler (and possibly quicker) when you are processing and displaying the returned records.

it would be easier for you to do it in php looping through the result of a query and adding the volume to a variable so that the variable can then be output each time.
If it must be done in the SQL as chrishirst said you need a stored procedure which would act much the same.