## Monday, 16 October 2017

### Getting information about referenced and referencing tables

At times we do need to carry out some tasks related to figure out certain information about references among some database objects. Today's post is going to show an example for tables by using T-SQL. There are two SQL Server system views we will use to query that information, they are 'sys.objects' and 'sys.sysreferences'. The view 'sys.objects' contains information for each database object (DDL and DML triggers) created inside of a particular user schema, and sys.sysreferences has the following important columns which will give us the object id of the referenced and referencing object.
• rkeyid: Contains the ID of the object which is being referenced.
• fkeyid: Contains the ID of the object which is referencing.
For instance, now we are going to figure out which tables are being referenced from the 'Product' table inside the 'AdventureWorks' database:

SELECT S.[name] AS 'Referenced Table'
FROM sys.objects S INNER JOIN sys.sysreferences R
ON S.OBJECT_ID = R.rkeyid
WHERE S.[type] = 'U' AND R.fkeyid = OBJECT_ID('[Production].[Product]')

Having done that, we can also figure out which tables are referencing to the 'Product' table.

SELECT S.[name] AS 'Referencing Table'
FROM sys.objects S INNER JOIN sys.sysreferences R
ON S.OBJECT_ID = R.fkeyid
WHERE S.[type] = 'U' AND R.fkeyid = OBJECT_ID('[Production].[Product]')

As I said earlier, not only can we use those views for tables, but also for other objects like functions, stored procedures, views, etc. I hope you can make the most out of this tip. Let me know any remarks you may have. Stay tuned.

## Friday, 13 October 2017

### Purging old backup files by using forfiles windows tool

It is well know that most backup strategies include a step to purge backup files to keep the most recent backups in the database server so that the disk space can be used properly. It is of paramount importance to schedule this task inside a SQL job in order to avoid running out of space. Today I am going to share a script to do that that uses forfiles windows tool via cmdshell. This script is within a stored procedure which has some input paramaters such as the database name, backup type, drive, and retention days.

USE [master]
GO
CREATE PROCEDURE [dbo].[sp_DBA_Backup_FilesCleanup] (
@DatabaseName VARCHAR(200),
@BackupType VARCHAR(100),
@DriveName VARCHAR(1),
@RetentionDays VARCHAR(4))
WITH ENCRYPTION
AS
BEGIN
SET NOCOUNT ON

DECLARE @strcmd VARCHAR(4000)
DECLARE @directory VARCHAR(4000)

SET @directory=@DriveName + ':\SQLBackup\' + @DatabaseName --+ '\'  + @BackupType
SET @strcmd='forfiles /p "'+@directory+'" /s /d -'+ @RetentionDays +' /c "cmd /c del /q @path"'
-- print @strcmd
EXEC master.dbo.xp_cmdshell   @strcmd

SET NOCOUNT OFF
END
GO

The logic deletes old backups files located on a path with this pattern '<Drive>:\<BackupDirectory>\<DatabaseName>\<BackupType>'. For instance, if we want to delete Full + Diff + Log Backup Files of the database 'MyDB' older than one week and supposing that those backups files are located on the drive 'G' then the full path would be 'G:\SQLBackup\MyDB\Full' for Full Backups, 'G:\SQLBackup\MyDB\Diff' for Differential Backups, and 'G:\SQLBackup\MyDB\Log' for Log Backups. So, using the following stored procedure and according to the example above, we should execute it with the following parameters:

USE [master]
GO
EXEC dbo.sp_DBA_Backup_FilesCleanup  @DatabaseName='MyDB' , @BackupType='FULL',@DriveName='G', @RetentionDays='7'
GO
EXEC dbo.sp_DBA_Backup_FilesCleanup  @DatabaseName='MyDB' , @BackupType='Diff',@DriveName='G', @RetentionDays='7'
GO
EXEC dbo.sp_DBA_Backup_FilesCleanup  @DatabaseName='MyDB' , @BackupType='Log',@DriveName='G', @RetentionDays='7'

That is all for now. Let me know any remarks you may have. Stay tuned.

## Monday, 2 October 2017

### Getting useful information of data & log files for all databases

It is a common DBA task to check the unused space of all database files in order to make the decision of extending the file sizes and provide them with more disk hard space in the likely event of running out of it. Today I have two scripts I would like to share with you to get that info easily. The first one is to report some very important information about every data & log file for all databases such as name, file size in GB, space used in GB, free space in GB and percentage, growth settings in tandem with other information at database level such as collation, compatibility level, owner, and more. Here you are:

USE master
GO
IF EXISTS (SELECT name FROM master.sys.tables WHERE name='TmpFileSpace')
DROP TABLE TmpFileSpace

CREATE TABLE [dbo].[TmpFileSpace](
[DatabaseName] [nvarchar](128) NULL,
[FileName] [sysname] NOT NULL,
[FileSizeGB] [decimal](10, 2) NULL,
[SpaceUsedGB] [decimal](10, 1) NULL,
[SpaceFreeGB] [decimal](10, 1) NULL,
[SpaceFree%] [decimal](10, 1) NULL
) ON [PRIMARY]

EXEC sp_MSforeachdb '
USE [?]
INSERT INTO master.dbo.[TmpFileSpace]([DatabaseName], [FileName], [FileSizeGB], [SpaceUsedGB], [SpaceFreeGB], [SpaceFree%])
SELECT DB_NAME() DatabaseName, name FileName,
CAST(size/128.0/1024.0 AS DECIMAL(10,2)) SizeGB,
CAST(FILEPROPERTY(name,''SpaceUsed'') /128.0/1024.0  AS DECIMAL(10,1)) SpaceUsedGB,
CAST((size - FILEPROPERTY(name,''SpaceUsed'')) /128.0/1024.0 AS DECIMAL(10,1)) SpaceFreeGB,
CAST(((size - FILEPROPERTY(name,''SpaceUsed''))/(size*1.0)) *100 AS DECIMAL(10,1)) [SpaceFree%]
FROM sys.database_files'

SELECT db.name DatabaseName,db.collation_name,db.compatibility_level, SUSER_SNAME(owner_sid) OwnerName,
db.page_verify_option_desc, db.is_auto_close_on,
db.is_auto_create_stats_on,db.is_auto_shrink_on, db.is_auto_update_stats_on,
db.is_auto_update_stats_async_on,db.name DatabaseName,  fs.FileName,
fs.FileSizeGB , fs.SpaceUsedGB, fs.SpaceFreeGB, fs.[SpaceFree%],
physical_name, cast(size/128.0/1024.0 as decimal(10,2)) FileSizeGB,
db.state_desc,max_size,growth,is_percent_growth
FROM sys.master_files mf
INNER JOIN sys.databases db ON mf.database_id = db.database_id
INNER JOIN TmpFileSpace FS ON mf.database_id=db_id(Fs.DatabaseName) AND mf.name=fs.FileName

DROP TABLE [TmpFileSpace]

But if you only want to get information about the size in GB, space used in GB, free space in GB of all data & log files for a specific database you can use this:

USE [YourDatabaseName]
SELECT DB_NAME() DatabaseName, name FileName,
CAST(size/128.0/1024.0 AS DECIMAL(10,2)) SizeGB,
CAST(FILEPROPERTY(name,'SpaceUsed') /128.0/1024.0  AS DECIMAL(10,1)) SpaceUsedGB,
CAST((size - FILEPROPERTY(name,'SpaceUsed') ) /128.0/1024.0 AS DECIMAL(10,1)) SpaceFreeGB,
CAST(((size - FILEPROPERTY(name,'SpaceUsed') )/(size*1.0)) *100 AS DECIMAL(10,1)) [SpaceFree%]
FROM SYS.database_files

That is all for now. Let me know any remarks you may have.
HELLO, I'M PERCY REYES! — a book lover, healthy lifestyle lover... I've been working as a senior SQL Server Database Administrator (DBA) for over 20 years; I'm a three-time awarded Microsoft Data Platform MVP. I'm currently doing a PhD in Computer Science (cryptography) at Loughborough University, England — working on cryptographic Boolean functions, algorithmic cryptanalysis, number theory, and other algebraic aspects of cryptography. READ MORE