Sum in Query

[ysurya]

I have a table:
ID_____Mat_____ DelvDate_____Qt yDelv
1_____ A ______10Jan07__ _____10
2_____ A ______12Jan07__ _____ 5
3_____ A _______8Jan07__ _____ 3
4_____ B ______10Jan07__ _____ 4
I want to create a query that will return the following result:
ID_____Mat_____ DelvDate______X
1_____ A ______10Jan07__ _____3
2_____ A ______12Jan07__ _____13
3_____ A _______8Jan07__ _____0
4_____ B ______10Jan07__ _____4
Note: X = sum of qty delivered before each delivery date
How could I achieve this?

[Rabbit]

Use a subquery to return the sum.