Question : Basic math in MS SQL stored procedure across three tables

I'm trying to do some very basic math in MS SQL by using one stored procedure to SUM the value of a column in Table_A, then divide the SUM from Table_A by the page view total from Table_B - and UPDATE the value in Table_C.

Basically I'm trying to work out the eCPC for a lead generating site on a page view basis (so every time a user visits a profile the eCPC is updated against the SUM of leads generated).

val = common denominator across all three tables

So step 1 is:
SELECT SUM(lead_value) as lead_sum FROM Table_A WHERE camp_id='val'

Step 2:
SELECT page_views FROM Table_B WHERE camp_id='val'

Step 3:
new_eCPC = lead_sum / page_views

Step 4:
UPDATE Table_C SET lead_eCPC='new_eCPC' WHERE camp_id='val'

Now I can easilly do this in ASP, but I have to execute an SQL script three times to do this - which I believe is terribily inefficient as I want it to happen each time a profile is viewed.

Can someone please help we write a stored procedure for this so I only have to execute it once on each profile view?

Many Thanks!

C

Answer : Basic math in MS SQL stored procedure across three tables

Well i cannot see what datatypes your fields have, but should be someting like the following.

You can execute it like this: EXEC UpdateECPC 'campid'

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CREATE PROCEDURE UpdateECPC @camp_id varchar(20)
AS
BEGIN
	SET NOCOUNT ON
	DECLARE @lead_sum int
	DECLARE @page_views int
	SET @lead_sum = (SELECT SUM(lead_value) FROM Table_A WHERE camp_id = @camp_id)
	SET @page_views = (SELECT page_views FROM Table_B WHERE camp_id = @camp_id)
	UPDATE Table_C SET lead_eCPC = @lead_sum / @page_views WHERE camp_id = @camp_id
	SET NOCOUNT OFF
END