Need help in setting up a discount of Rs2000

 Hello Friends,

1.Can anybody suggest me how should I setup a discount of Rs 2000 if the condition is such that

if customer "A" buys item "X" of 700 qty then he should get 2000 Rs discount off only for 1st time and only once in order. If he adds more lines in same order or creates a new order it shpuld be processed normally without 2000 Rs discount. Any suggestion ??

2. How does coupon option works in oracle. can it be impleented for above example by giving some coupon nos.