Finding sum based on the condition in Sql Server 2008

Question

I have these columns in my table

Person      Agent     Unit        BSP            Discount

---

578           0      000023      32689525       0.1
578           1      000025      17589656       1
579           0      000021      32689525       0.1
579           0      000020      17589656       1
581           0      000022      32689525       0.1
583           0      000024      17589656       1
578           11     000023q     32689525       0
578           12     000025a     17589656       0

Actually I have to calculate the incentive for Person . Say in case of above 578. Since It has booked total 4 units out which 3 are with brokers and 1 is individual. So from broker part his incentive will 2500 INR per unit that is 3*2500 = 7500. Now comes the discount part. See the points below:

Conditions:

1. If No discount has been given, than 1% of BSP will be allocated to Incentive to the Sales Person.

2. If Discount given to booking is between .1% to 1%, than .75% of BSP will be allocated to Incentive to the Sales Person.

3. If Discount given to booking is between 1 .1% to 2%, than .50% of BSP will be allocated to Incentive to the Sales Person.

4. If Discount given to booking is between 2% and above, than .25% of BSP will be allocated to Incentive to the Sales Person.

In the above tables it us clear that 578 has booked 4 units, two with discounts an two without discounts.

So his incentive will be calculated as :

  var incentive = total_no_of_units_booked_with_agent * 2500;

// since there might be a possibility that more than one units can be
// booked by a sales person.No we have to find if there is any discount 
// applied there, if its there, then extract the incentive for each unit 
//and total it using the above condition. For table shown we have
//since it has 4 records

  incentive = incentive + (.75% of BSP)+ (.75%of BSP)+(1% of BSP)+(1%of BSP) 

Answer 1

For a conditional sum, just use SUM with a CASE statement inside it to enforce your conditions.

SELECT
  person,
  SUM(CASE WHEN discount  = 0.00 THEN 0.0100 * bsp
           WHEN discount <= 0.01 THEN 0.0075 * bsp
           WHEN discount <= 0.02 THEN 0.0050 * bsp
                                 ELSE 0.0025 * bsp END
      +
      CASE WHEN agent <> 0       THEN 2500.0
                                 ELSE    0.0       END)  AS incentive
FROM
  yourTable
GROUP BY
  person