Parameterized sorting in SQL Server

Applications that allow users to sort data by different columns of the table might need to go for dynamic stored procedures or will end up in adding multiple procedures based on the number of combinations. In SQL Server we can achieve this easily through parameterized sorting.
As shown in the below example we can have a parameter which says the column on which the sort criteria can be applied and using the case statement we achieve the results without going for a dynamic /multiple stored procedures.

DECLARE @SortOrder INT
SET @SortOrder =1
SELECT ForeName,
SurName,
PASID
FROM PAtient
WHERE Forename LIKE 'A%'
ORDER BY CASE WHEN @SortOrder = 1 THEN ForeName
WHEN @SortOrder = 2 THEN SurName
ELSE PASID
END

Generate Index scripts using included columns

This article is a continuation of the previous article http://samsudeenb.blogspot.com/2007/11/scripts-to-drop-and-recreate-indexes-in.html with small enhancement to generate the index scripts with included columns. The below function “fGetIncludedIndex is used to get the included columns for a given index.

CREATE FUNCTION fGetIncludedIndex (
@objname VARCHAR(50),
@indid INT
)
RETURNS NVARCHAR(200)
AS
BEGIN
DECLARE @V_IncludedCol NVARCHAR(200)
select @V_IncludedCol = COALESCE(@V_IncludedCol + ',', '') +
( select name from sys.syscolumns where id =a.Object_id and colid =a.column_id)
from sys.index_columns a
where object_name(a.object_id) =@objname
and a.index_id =@indid
and a.Is_included_column =1
order by a.index_column_id
return @V_IncludedCol
END

After creating the function in the DB make a small change to the existing query( highlighted in bold) to generate the index scripts with included columns

SELECT 'CREATE ' +
CASE IS_UNIQUE WHEN 1 THEN 'UNIQUE ' ELSE ' ' END +
'NONCLUSTERED ' + ' INDEX '+
NAME + ' ' +' ON ' +
OBJECT_NAME (OBJECT_ID) +
'('+
DBO.fGetIndexCols (object_NAME(OBJECT_ID), index_id) + ')'
+Case when dbo.fGetIncludedIndex(object_NAME(OBJECT_ID), index_id) is null then '' else ' INCLUDE ('+dbo.fGetIncludedIndex(object_NAME(OBJECT_ID), index_id)+')' end +
' ON ['+
( SELECT GROUPNAME
FROM SYSFILEGROUPS
WHERE GROUPID = DATA_SPACE_ID
) + ']' IndexScript
FROM SYS.INDEXES
WHERE NAME IS NOT NULL
AND Is_Primary_Key =0
AND type_desc ='NONCLUSTERED'
AND OBJECT_ID > 97

How to take week or month wise report in SQL Server

I was breaking my head whole day for writing a stored procedure which produces week wise report for plotting a revenue trend. I came across this solution which is fairly a simple one. Just thought of sharing this

The below code is written using the SQL Server built in functions DATEDIFF & DATEADD to produce the report

Select DATEADD(WK, datediff(WK, 0, CollectionDate),0) as week,
SUM(Amount)
from Revenue
group by dateadd(WK, datediff(WK 0, CollectionDate),0)
order by 1 asc

The logic here is to find out the corresponding week from Default date (01-01-1900) and adding the default date again to the result will get the corresponding week in date format. The same can be used for generating month wise report as well by just replacing "wk" with "MM"

Select DATEADD(MM, datediff(MM, 0, CollectionDate),0) as week,
SUM(Amount)
from Revenue
group by dateadd(MM, datediff(MM 0, CollectionDate),0)
order by 1 asc

Note: adding “0” will be automatically converted to default date “01-01-1900”

How to generate Sequence number in SQL Server

Sequence number generation is one of the common requirements in all the OLTP applications.SQL Server supports many ways to generate Sequence numbers. The below example explains how to generate multiple sequences dynamically using the SQL Server

Schema Design

This table will hold the configuration parameters for each of the Sequence Types (eg: PurchaseOrder, GRN etc).The column “SequenceName” column will have the unique code for each Sequence type and the “TableName” column is used to map the name of the “IDGenerator” table. (I.e. multiple IDGenerator tables can be created with the same structure and mapped accordingly)

ID Generation:
The below stored procedure pGetSEQID is used to generate the new sequence number .It accepts the table name as input and return the new sequence number. Since the IDGenerator table can be different for each ID type the stored procedure is written as dynamic.

CREATE PROCEDURE pGetSEQID (
@P_SEQTableName VARCHAR(30)
)
AS
BEGIN
DECLARE @V_SEQValue BIGINT
DECLARE @V_SQLString NVARCHAR(200)
DECLARE @V_ParmDefinition NVARCHAR(200)
DECLARE @V_SEQTableName VARCHAR(30)
SET @V_ParmDefinition = N'@V_SEQValue BIGINT OUTPUT'
SET @V_SQLString = N'INSERT INTO ' +
@P_SEQTableName +
N'(Status) values (''Y'') SELECT @V_SEQValue = SCOPE_IDENTITY()'
exec sp_executesql @V_SQLString,@V_ParmDefinition ,@V_SEQValue =@V_SEQValue OUTPUT
SELECT @V_SEQValue NewSequenceValue
END

EXEC pGetSEQID ‘PurchaseOrder’ will generate the Sequence Number for ID type purchase order

We can make use of Prefix and Suffix columns in the IDParamter table to generate the Sequence number with the required format
Eg: “BL0001” , BL100/0908

How to Select Data in Random Order in SQL Server

In number of scenarios we might want to do data sampling or select the data in a Random Order. SQL Server supports various options for data sampling. I have given some of the examples here

Using NEWID() :
SELECT TOP 10 ForeName
FROM Patient
ORDER BY NEWID()

Using PERCENT
SELECT TOP 10 ForeName
FROM (SELECT TOP 30 PERCENT ForeName
FROM Patient
ORDER BY ForeName ASC) AS Pat
ORDER BY 1 DESC

How to find the Database Restore Details in SQL Server 2008

It is often useful to know the details from where the database is restored.The restore history of the database is stored in the msdb table "restorehistory".I recently came across this query which gives the complete information of restore history including the Restored Login , From & To Location of the Files

SELECT
rsh.destination_database_name AS [Database],
rsh.user_name AS [Restored By],
CASE WHEN rsh.restore_type = 'D' THEN 'Database'
WHEN rsh.restore_type = 'F' THEN 'File'
WHEN rsh.restore_type = 'G' THEN 'Filegroup'
WHEN rsh.restore_type = 'I' THEN 'Differential'
WHEN rsh.restore_type = 'L' THEN 'Log'
WHEN rsh.restore_type = 'V' THEN 'Verifyonly'
WHEN rsh.restore_type = 'R' THEN 'Revert'
ELSE rsh.restore_type
END AS [Restore Type],
rsh.restore_date AS [Restore Started],
bmf.physical_device_name AS [Restored From],
rf.destination_phys_name AS [Restored To]
FROM msdb.dbo.restorehistory rsh
INNER JOIN msdb.dbo.backupset bs ON rsh.backup_set_id = bs.backup_set_id
INNER JOIN msdb.dbo.restorefile rf ON rsh.restore_history_id = rf.restore_history_id
INNER JOIN msdb.dbo.backupmediafamily bmf ON bmf.media_set_id = bs.media_set_id


You can apply filter criteria such as the restore date , Database by addding a where clause to the existing query as shown below

WHERE
rsh.restore_date >= DATEADD(dd, "No of Past Days" , GETDATE())
AND destination_database_name = ISNULL( "DB Name", destination_database_name)
ORDER BY rsh.restore_history_id DESC

SQL Server 2008 - Performance white paper

Microsoft has release its latest white paper on SQL Server 2008 performance trouble shooting.This article provides steps to diagonse the common performance problems faced by Microsoft CSS team.The following areas are covered in depth

• CPU Bottlenecks
• Memory Bottlenecks
• IO Bottlenecks
• Temp DB
• Slow Running Queries
• Extended Events
• Data Collector & MDV

The new features of SQL Server 2008 such as Extended Events & Data Collector are covered in detail .It is worth to have a look at this long running ( 102 pages) document. It is avilable for download at
http://msdn.microsoft.com/en-us/library/dd672789.aspx