Working wth Variables in Database Interactions with Transact-SQL - Using T-SQL variables efficiently: continued

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We all know that finding the sum of values is very easy using the aggregate SUM as follows:

SELECT sum(UnitPrice * Quantity)
FROM [Order Details]

We can retrieve the sum in to a variable in a script as follows:

use Northwind
go
declare @sum numeric(10,2)

SELECT @sum = sum(UnitPrice * Quantity)
FROM [Order Details]

print @sum
go

The same can be achieved by further simplifying it as follows:

use Northwind
go
declare @sum numeric(10,2)

SET @sum = (SELECT sum(UnitPrice * Quantity)
FROM [Order Details])

print @sum
go

We can also use the recursive method as follows:

use Northwind
go
declare @RunningSum numeric(10,2)
set @RunningSum = 0.0

SELECT @RunningSum = @RunningSum + sum(UnitPrice * Quantity)
FROM [Order Details] as a

print @RunningSum
go

In the next article, I shall concentrate a bit more on variables, conditions, loops, DML statements and so forth. So please check back frequently or sign up for a newsletter! Any bugs, errors, improvements etc., are highly appreciated at http://jagchat.spaces.live.com.

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