what is the value when running sql script?
select cast(cast(.0000006 as numeric(38,10)) * cast(1.0 as numeric(38,10)) as numeric(38,10))
the result is .0000010000.
why the result is not .0000006000?
When I run the following code :
DECLARE @var1 float,
@var2 int;
SET @var1 = 32.91 ;
SET @var2 = 100 ;
SELECT CAST(@var1 * @var2 AS int);
the result is ... 3290 (whereas it should be 3291 !)
Also works for @var1 set to 33.91 34.91 35.91 36.91 37.91 38.91 39.91 but not for other values > 40.
Is that a SQL Server bug ?
Does multiplication with 1 affect query performance?I have a a stored procedure that converts results to another unit if required. In alternative 1 below, the results are returned with a separate select statement if no conversion is necessary - in other words, no multiplication with a conversion factor is required. However, the code is not very nice since I need to repeat the select statement again in case a conversion is required, this time including the conversion factor.Alternative 2 uses cleaner-looking code. The conversion factor is set to 1 if no conversion is required, and a single SELECT statement is used to return the data. The @factor variable is defined as a float.I would rather use alternative 2, but I wonder if there is any performance penalty for doing that if no conversion is required since the results are always multiplied with the @factor? Or can SQL server somehow understand that @factor = 1 and no multiplication is required?--- Alternative 1: ---IF @fromunit_sid = @tounit_sid-- Return unconverted results
SELECT ISNULL(ls_totalWaterConsumption,0) AS ls_totalWaterConsumption,ls_theoreticalWaterConsumption AS ls_theoretical_WaterConsumption,ls_totalWaterConsumption - ls_theoreticalWaterConsumption AS ls_extra_WaterConsumption FROM Results WHERE scenario_id = @scenario_idELSEBEGIN
-- Get conversion factor
EXEC getConversionFactor @fromunit_sid, @tounit_sid, @factor OUTPUT -- Get the converted results
SELECT ISNULL(ls_totalWaterConsumption * @factor,0) AS ls_totalWaterConsumption, ls_theoreticalWaterConsumption * @factor AS ls_theoretical_WaterConsumption, (ls_totalWaterConsumption - ls_theoreticalWaterConsumption) * @factor AS ls_extra_WaterConsumptionFROM Results WHERE scenario_id = @scenario_idEND --- Alternative 2: ---IF @fromunit_sid = @tounit_sidSET @factor = 1ELSE
-- Get conversion factor
EXEC getConversionFactor @fromunit_sid, @tounit_sid, @factor OUTPUT
-- Get the converted results
SELECT ISNULL(ls_totalWaterConsumption * @factor,0) AS ls_totalWaterConsumption, ls_theoreticalWaterConsumption * @factor AS ls_theoretical_WaterConsumption, (ls_totalWaterConsumption - ls_theoreticalWaterConsumption) * @factor AS ls_extra_WaterConsumptionFROM Results WHERE scenario_id = @scenario_id And another question: is using an IF function considerably faster than making a call to another stored procedure?In alternative 2 above I use an IF statement to check if @fromunit_sid = @tounit_sid, and . But in fact the function getConversionFactor that I'm calling does exactly the same thing: if I pass in identical from- and to-values, it simply returns 1, so I could omit the IF statement completely and just use alternative 3. But is it slower?--- Alternative 3 -- Get conversion factor
EXEC getConversionFactor @fromunit_sid, @tounit_sid, @factor OUTPUT
-- Get the converted results
...
Hi all...I have a friend who has a problem I'm trying to help with (no...REALLY...it's a FRIEND, not ME!!! *LOL*)
I haven't run across the need...but in a nutshell...we have a table with many rows of data, one column in each row needs to be multiplied by all other same-columns in the table's other rows.
For example...
MyKey int, MyFloat float(53)
I want to multiply Myfloat by all other Myfloat columns in the table.
Similar to SUM(MyFloat) but something like PRODUCT(MyFloat).
Is there a aggregate kept in a basement closet somewhere, or a way to perform this operation rather than using a cursor to do it:
An example of my table:
1 3.2
2 4.1
3 7.1
if I could do a PRODUCT(MyFloat) I would want the result to be (3.2 X 4.1 X 7.1) or 93.152
Do I have to do this with a cursor?
Thanks!
Paul
I am currently building a website to deal with different product information and sales with php. I am using SQL to sort the database and pull out information.
The final thing i need to do is work out the total revenue of each product however the problem i am having is that the 'Price' column and 'SalesVolume' column are in two different tables and they need to be multiplied together.
The two tables and column headings are as follows:
Product
ID
Name
Price
MonthlySales
ID
ProductCode
Month
Year
SalesVolume
(ID and ProductCode are linked together in a relationship)
I cannot see anything wrong with the syntax in my query however i believe there is.
Here is the query I am using:
Code:
"SELECT SUM(Products.Price * SUM(MonthlySales.SalesVolume)) as revenue FROM Products
INNER JOIN MonthlySales ON(Products.ProductCode = MonthlySales.id) GROUP BY Products.ProductCode";
I'm trying to create a case statement that if a field = a certain code, I'd like to take another field * 0.9. But, I'm getting a Null value for the answer..here is the statement:,case when parts.ndc = '50242-0138-01' then labels.BAGSDISP*0.9 end "Units Dispensed"..For this example labels.BAGSDISP is a value of 2. So, in theory it should be 2 * 0.9 and the result should be 1.8 but I'm getting a NULL
View 9 Replies View RelatedSuppose I have users that can belong to organizations. Organizationsare arranged in a tree. Each organization has only one parentorganization but a user maybe a member of multiple organizations.The problem that I'm facing that both organizations and individualusers may have relationships with other entities which aresemantically the same. For instance, an individual user can purchasethings and so can an organization. An individual user can havebusiness partners and so can an organization. So it seems that I wouldneed to have a duplicate set of link tables that link a user to apurchase and then a parallel link table linking an organization to apurchase. If I have N entities with which both users and organizationsmay have relationships then I need 2*N link tables. There is nothingwrong with that per se but just not elegant to have two differenttables for a relationship which is the same in nature, e.g.purchaser->purchaseditem.One other approach I was thinking of is to create an intermediateentity (say it's called "holder") that will be used to hold referencesto all the relationships that both an organization and an individualmay have. There will be 2 link tables linking organizations to"holder" and users to "holder". Holder will in turn reference thepurchases, partners and so on. In this case the number of link tableswill be N+2 as opposed to 2*N but it will have a performance cost ofan extra join.Is there a better way of modelling this notion of 2 different entitiesthat can possess similar relationships with N other entities?
View 28 Replies View Related