In this post, I am sharing an aggregate query for calculating Multiplication for each group in SQL Server. We are using an aggregate function like MAX(), SUM(). But there is no any aggregate function for Multiplication.

We can use EXP/LOG expression for this exercise. EXP returns the exponential value and LOG returns the natural logarithm of the specified float expression.

Please check the below demonstration:

Create a table with sample data:

CREATE TABLE tbl_GroupNumber (GroupName VARCHAR(10), GroupValue INT)

INSERT INTO tbl_GroupNumber VALUES
('A',10),('B',15),('C',20),('D',30)
,('B',30),('C',60),('D',40),('D',50)
,('A',70),('B',40),('C',10),('B',90)
GO

Solution:

SELECT 
	GroupName 
	,EXP(SUM(LOG(GroupValue))) AS GroupValue
FROM tbl_GroupNumber
GROUP BY GroupName

Result:

GroupName  GroupValue
---------- ----------------------
A          700
B          1620000
C          12000
D          60000

In this post, I am sharing a demonstration in which you can get to know that committed inner transactions are not releasing any log disk space in SQL Server.

One of our developers was telling me like when we commit the transaction it will release the occupied log space, but it is not entirely correct.
If you are dealing with nested transactions, it is true only for outer committed transactions.

Please check the below demonstration of this.

Create a sample database:

CREATE DATABASE Test_Tran;
GO
USE Test_Tran
GO

Check the log size:

CHECKPOINT
GO
DBCC SQLPERF ('LOGSPACE')
GO
-- the result
-- 4.557673

Create a sample table:

CREATE TABLE tbl_TestTrans(ID INT)
GO

Open outer and inner transaction and insert few sample records:

BEGIN TRANSACTION OuterTrans
GO
	BEGIN TRANSACTION InnerTrans
	GO
		INSERT INTO tbl_TestTrans VALUES(88)
		GO 1000
	COMMIT TRANSACTION InnerTrans
	GO

Check the log size:
The inner transaction is committed, but log size is increased, and it didn’t release the logs.

CHECKPOINT;
GO
DBCC SQLPERF ('LOGSPACE');
GO

-- the result:
-- 8.767107

Now, commit outer transaction:

COMMIT TRANSACTION OuterTrans
GO

Check the log size:
Once you commit your outer transaction, it releases the log size.

CHECKPOINT;
GO
DBCC SQLPERF ('LOGSPACE');
GO

-- the result:
-- 5.08