# 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:

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

Step 3:

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
###### Who is Participating?

Commented:
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'

``````CREATE PROCEDURE UpdateECPC @camp_id varchar(20)
AS
BEGIN
SET NOCOUNT ON
DECLARE @page_views int
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
``````
0

Commented:
Something like this perhaps:
``````U PDATE  c
FROM    Table_C c
FROM    Table_A
WHERE   camp_id = 'val'
) a ON c.camp_id = a.camp_id
INNER JOIN Table_B b ON c.camp_id = b.camp_id
``````
0

Commented:
try
``````Create procedure yourProc (@camp_id varchar(20))
As
Begin
declare @new_eCPC int
SELECT @new_eCPC = @lead_sum / page_views  FROM Table_B WHERE camp_id=@camp_id
UPDATE Table_C SET lead_eCPC= @new_eCPC WHERE camp_id=@camp_id
end
``````
0

Commented:

Create procedure Proc_name (@camp_id varchar(50))
As
declare @sum_A int
declare @div
Begin
SELECT @div = @sum_A /SUM(page_views)  FROM Table_B WHERE camp_id=@camp_id
UPDATE Table_C SET lead_eCPC= @div WHERE camp_id=@camp_id
end

0

Author Commented:
That is brilliant! Thanks very much guys - I don't use stored procedures very often so wasn't aware you could declare variables that easilly and execute multiple lines.
0

Commented:
Strange choice.  Multiple SELECT statements over a single UPDATE statement?  Obviously performance is not important to you.
0
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