Category Archives: tsql

How to grant a User SELECT permission on multiple tables in SQL Server using T-SQL and Excel Formulas

Maybe you get emails from time to time saying something like “Hey can you grant so-and-so SELECT permission on” and then they list a few dozen tables.

There’s a couple of issues with this.

Firstly you shouldn’t be getting that as a simple email, it should come in as a formal access request.

Secondly User access should be defined in roles (or group logins if you want to manage access at an Active Directory level) that tie back to departments and seniority. Different roles have different permissions on different objects. This makes the subject of access more manageable and easily auditable. The access request should be “can you add so-and-so to this role” and ideally people should only exist in one role.

Thirdly this would be really annoying and, depending on the length of the table list, take too long to do via the SSMS GUI.

So if you are getting emails like the above try move your organisation along with regards the first two points. But to help you action the email I’ve created the Excel file DbaScripts_GrantSelect which can be downloaded here.

Grant Select Excel Sheet Snippet

The DbaScripts_GrantSelect file allows you to enter the Login (user name), Database name and Schema name in the first three columns. You can then copy and paste the table names into the fourth column called Table. Drag the first three columns down for as many table name entries there are. Then drag the SQL Command formula column down for as many table name entries there are and this will create the commands to grant SELECTs on the tables for the user specified.

If you can’t download the file above you can recreate it.

In an empty Excel sheet write the following into the cells as directed.

A1: Login
B1: Database
C1: Schema
D1: Table
E1: SQL Command

In E2 paste the following formula:

=”GRANT SELECT ON [“&B2&”].[“&C2&”].[“&D2&”] TO [“&A2&”];”

 

Find and drop every table in a SQL Server Database that contains specific text in the table name

GDPR compliance has given people working in the DBA space the exciting opportunity to drop tables! Tables once considered gold mines are now being treated like live grenades management want rid of fast. This is a prudent stance because if a table contains personal data and it’s not being used for some vital business process why keep it around now? If somehow the wrong person gained access to the data it could have severe reputational and financial consequences. Of course a business should have never kept unneeded personal data but in truth most companies have gathered as much data as they could up until this point even if it wasn’t used as the assumption has been it might be needed later.

Before dropping tables though it is still good practice to rename the table first for a period of time to make sure nothing breaks. Once a sufficient amount of time has passed and you are confident the tables can be dropped without adverse effects the script below can help drop the newly unwanted tables.

If you’ve followed a standard naming convention for renaming unwanted tables, for example prefixing all the targeted tables with “_DropThis_” or something to that effect, this script will provide commands to:

  • Count the number of rows in each targeted table
  • Drop each targeted table
  • Confirm each targeted table has been dropped.

Simply find & replace the text “DatabaseName” with the name of the database that contains the tables to be dropped and “TextTarget” with the text each table name should contain and run the script.

Running the script will produce two tables. The first table will contain the commands to count the number of rows for each targeted table. The second table will contain the commands to drop each targeted table. Open new windows in SSMS, referencing the database to run the commands against, and copy and paste the scripts of each table into the windows. Run the count script first obviously before the drop script. Once the drop script has been run you can run the commented out query at the end of the script below to confirm the tables have been dropped.

You can take the screen shots and/or copy and paste the results of the commands (and the commands themselves) into an email or text document as a simple report to confirm the number of rows dropped and that the tables have been dropped.

/*
Find & Replace:
DatabaseName
TextTarget
*/
USE [DatabaseName];
GO

DECLARE @keyword AS VARCHAR(MAX);
DECLARE @MaxRow AS INT;

SET @keyword = 'TextTarget'

IF OBJECT_ID('tempdb.dbo.#TableStats', 'U') IS NOT NULL
	DROP TABLE #TableStats;

IF OBJECT_ID('tempdb.dbo.#CountCommand', 'U') IS NOT NULL
	DROP TABLE #CountCommand;

/*
Confirm Table Existance
*/
SELECT s.NAME AS SchemaName
	,t.*
INTO #TableStats
FROM sys.tables AS t
LEFT JOIN sys.schemas AS s ON t.schema_id = s.schema_id
WHERE t.NAME LIKE '%' + @keyword + '%'
ORDER BY s.NAME ASC
	,t.NAME ASC;

/*
Create Count SQL Commands
*/
SELECT ROW_NUMBER() OVER (
		ORDER BY [--SqlCommand]
		) AS Row#
	,[--SqlCommand]
INTO #CountCommand
FROM (
	SELECT 'SELECT ''' + s.NAME + '.' + t.NAME + ''' AS SchemaTableName, COUNT (*) AS [TableRowCount] FROM ' + QUOTENAME(s.NAME) + '.' + QUOTENAME(t.NAME) + ' WITH (NOLOCK) UNION ALL' AS [--SqlCommand]
	FROM sys.tables AS t
	LEFT JOIN sys.schemas AS s ON t.schema_id = s.schema_id
	WHERE t.NAME LIKE '%zzz%'
	) AS SqlCommand
ORDER BY [--SqlCommand];

SET @MaxRow = (
		SELECT MAX(Row#)
		FROM #CountCommand
		);

UPDATE #CountCommand
SET [--SqlCommand] = LEFT([--SqlCommand], LEN([--SqlCommand]) - 9)
WHERE Row# = @MaxRow;

UPDATE #CountCommand
SET [--SqlCommand] = [--SqlCommand] + ';'
WHERE Row# = @MaxRow;

SELECT *
FROM #CountCommand
ORDER BY [--SqlCommand];

/*
Create Drop Table SQL Commands
*/
SELECT 'DROP TABLE ' + QUOTENAME(s.NAME) + '.' + QUOTENAME(t.NAME) + ';' AS '--DropTableSqlCommand'
FROM sys.tables AS t
LEFT JOIN sys.schemas AS s ON t.schema_id = s.schema_id
WHERE t.NAME LIKE '%' + @keyword + '%'
ORDER BY s.NAME ASC
	,t.NAME ASC;
/*
Run seperately
Confirm Tables are dropped
*/
	/*
SELECT s.NAME AS SchemaName
	,t.NAME AS TableName
FROM sys.tables AS t
LEFT JOIN sys.schemas AS s ON t.schema_id = s.schema_id
INNER JOIN #TableStats AS ts ON s.NAME = ts.SchemaName
	AND t.NAME = ts.NAME
ORDER BY s.NAME ASC
	,t.NAME ASC;
*/

 

How to schedule a job to restore the last backup made of a SQL Server database

This post provides you with a script that will generate a restore script for a database using the latest full backup file that exists in a directory. (No need to state the filename explicitly)

You need to provide the following at the start of the script:

  • The target database i.e. the database you will restore to
  • The directory where the backup file is saved

If you are using the excellent Ola Hallengren maintenance solution (see link) the directory path will look something like below. If you’re not using Ola’s solution, you should be.

\\ServerWhereBackupsAreSaved\DriveName\InstanceName\TargetDatabase\Full\

This restore script is designed to work with Ola’s solution as it segregates the backup directory structure such that each database has an allocated folder and each full backup file is named with the date and time of the file creation.

The restore script determines which backup file is the latest backup file based on the max name. So for the script to work it is assumed you have an appropriate backup strategy (i.e. using Ola’s solution) were backup types are segregated into different folders, backup names have a date reference and the backup location is dedicated to backups and nothing else, i.e. no trash files in the location.

Some use cases for this solution might be:

  • Restoring a nightly backup to another instance for reporting purposes
  • Restoring backups to a development environment
  • Restoring backups to another server to test the backups

You can use the logic in a stored procedure or as the T-SQL in a job step and schedule accordingly.

/*
You need to reference the following:
* The target database i.e. the database you will restore to.
* The directory where the backup file is saved.
If you are using the Ola Hallengren backup scripts the directory path will look 
something like below.
\\ServerWhereBackupsAreSaved\DriveName\InstanceName\TargetDatabase\Full\

Find & Replace the follow text for the target database and directory:

TARGET_DATABASE
DIR_PATH
*/
/*
Declare Variables
*/
DECLARE @DatabaseToRestore AS VARCHAR(MAX);
DECLARE @DirToSearch AS VARCHAR(MAX);
DECLARE @ShellCommand AS VARCHAR(MAX);
DECLARE @BackupFile AS VARCHAR(MAX);
DECLARE @Sql AS VARCHAR(MAX);

/*
Set User Variables
*/
SET @DatabaseToRestore = 'TARGET_DATABASE';
SET @DirToSearch = 'DIR_PATH';
SET @ShellCommand = 'dir ' + @DirToSearch;

/*
Create Temp Table To Hold xp_cmdshell Output
*/
IF OBJECT_ID('tempdb..#DirList') IS NOT NULL
	DROP TABLE #DirList;

CREATE TABLE #DirList (
	Id INT identity(1, 1)
	,line NVARCHAR(1000)
	);

/*
Enable Advanced Options To Enable xp_cmdshell Temporarily
*/
EXEC master.dbo.sp_configure 'show advanced options'
	,1;

RECONFIGURE
WITH OVERRIDE;

EXEC master.dbo.sp_configure 'xp_cmdshell'
	,1;

RECONFIGURE
WITH OVERRIDE;

/*
Run The Shell Command To Capture And Write Dir Info To Temp Table
*/
SET @Sql = '
INSERT INTO #DirList (line)
EXEC xp_cmdshell ' + '''' + @ShellCommand + '''' + ';';

EXEC (@Sql);

EXEC master.dbo.sp_configure 'xp_cmdshell'
	,0;

/*
Disable Advanced Options And xp_cmdshell Again
*/
RECONFIGURE
WITH OVERRIDE;

EXEC master.dbo.sp_configure 'show advanced options'
	,0;

RECONFIGURE
WITH OVERRIDE;

/*
Get The Last Backup File Name And Save To A Variable
*/
WITH CTE
AS (
	SELECT SUBSTRING(line, 37, 100) [FileName]
	FROM #DirList
	WHERE Id > (
			SELECT MIN(Id)
			FROM #DirList
			WHERE line LIKE '%<DIR>%..%'
			)
		AND Id < (
			SELECT MAX(Id) - 2
			FROM #DirList
			)
	)
SELECT @BackupFile = [FileName]
FROM CTE
WHERE [FileName] = (
		SELECT MAX(FileName)
		FROM CTE
		);

/*
Create The Restore Script
*/
SET @BackupFile = @DirToSearch + @BackupFile
SET @Sql = '
ALTER DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
RESTORE DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' FROM DISK = ' + '''' + @BackupFile + '''' + '
WITH NORECOVERY
,REPLACE;
RESTORE DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' WITH RECOVERY;
'

/*
To Directly Execute The Script Uncomment The EXEC Statement And Delete The Select Statement
*/
/*
EXEC (@Sql)
*/
SELECT @Sql

 

How to move and or rename Database files in SQL Server

An example use case for the process below could be you need to move database files to a new drive. Another example might be your organisation intends to run a legacy database along side a new updated database with both sharing the same database name in the same instance with the files located in the same directory with the same names. Obviously this cannot be done and requires the database names to differ and the files to be renamed or not exist in the same directory.

For example AdventureWorks might become AdventureWorks_Legacy while a new and improved AdventureWorks database retains the original database name. The associated database file names would also need to be changed/moved to reflect this.

Someone might also want to do something like this for test purposes but obviously having test resources in a live environment would not be recommended if avoidable.

The first step to moving and renaming the files is to copy and modify the script below. Note the script below assumes you want to move and change the names of the files. To avoid any database conflicts you only need to do one or the other.

/* 
Find & Replace DbName with the name of the Database you are working with
*/
USE [DbName];

/*
Changing Physical names and paths
Replace 'C:\...\NewDbName.mdf' with full path of new Db file to be used
*/
ALTER DATABASE DbName MODIFY FILE (
	NAME = ' DbName '
	,FILENAME = 'C:\...\NewDbName.mdf'
	);

/*
Replace 'C:\...\NewDbName_log.ldf' with full path of new Db log file to be used
*/
ALTER DATABASE DbName MODIFY FILE (
	NAME = ' DbName _log'
	,FILENAME = 'C:\...\NewDbName_log.ldf'
	);

/*
Changing logical names
*/
ALTER DATABASE DbName MODIFY FILE (
	NAME = DbName
	,NEWNAME = NewDbName
	);

ALTER DATABASE DbName MODIFY FILE (
	NAME = DbName_log
	,NEWNAME = NewDbName_log
	);
Once the script has been set up as desired follow the steps below:
  1. Open Microsoft SQL Server Management Studio (SSMS).
  2. Connect to the server that houses the Db you are working with.
  3. Run the modified script
  4. Right click on the Db in SSMS and select Tasks > Take Offline
  5. If you are moving the database files log into the server that houses the database files and copy and move the MDF and LDF files to the location you specified in first two alter commands. If the script specifies new names rename the copied files to match the names given in the script exactly.
  6. Go back to SSMS and right click on the Db and select Tasks > Bring Online.
  7. If you have moved the files once the database is back online and confirmed working as expected the unused original files can be deleted.
  8. Now you can rename the Db to the new name if you wish using SSMS.

How to demonstrate the space usage of a Null Varchar(Max) column

An empty Varchar(Max) column uses a negligible amount of disk space. The script below demonstrates this by creating the table TestTb which contains one column named NullColumn that has a Varchar(Max) data type. When the table is created the column NullColumn is populated with 100,000 rows of Null.

The two readings below show the table when it has just been created and the table with 100,000 rows entered.

Results

IF OBJECT_ID('dbo.TestTb', 'U') IS NOT NULL
	DROP TABLE dbo.TestTb;

CREATE TABLE TestTb (NullColumn VARCHAR(MAX));
GO

sp_spaceused 'TestTb';

DECLARE @i AS INT;

SET @i = 0;

WHILE @i < 100000
BEGIN
	INSERT INTO TestTb (NullColumn)
	VALUES (NULL)

	SET @i = @i + 1
END;
GO

sp_spaceused 'TestTb';

IF OBJECT_ID('dbo.TestTb', 'U') IS NOT NULL
	DROP TABLE dbo.TestTb;

 

How to determine why a T-SQL command is unreasonably slow

If you’ve ever found yourself in the situation were a command executing against a small table is nowhere near instant there can be numerous reasons for this but the most common causes are locks and waits.

The first step in identifying the problem is to execute the script below in a new query window while the troublesome command is running.

/* Queries Not Running */
SELECT ROW_NUMBER() OVER (
		ORDER BY r.total_elapsed_time DESC
		) AS Rn
	,st.TEXT AS SqlText
	,r.*
FROM sys.dm_exec_requests r
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS st
WHERE r.status <> 'running';

/* Queries Running */
SELECT ROW_NUMBER() OVER (
		ORDER BY r.total_elapsed_time DESC
		) AS Rn
	,st.TEXT AS SqlText
	,r.*
FROM sys.dm_exec_requests r
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS st
WHERE r.status = 'running';

 

This script will return two lists of the currently active sessions along with the stats associated with their execution. The first list will contain all the active sessions that are not running. The second list will contain all the active sessions that are running and will likely not contain the troublesome query you’re dealing with.

Identify your session based on the SqlText field. Be sure you’ve identified the session correctly as you may decide you want to kill the process later and killing the wrong one could cause you a lot of trouble.

  • status : If the status is not running look to the other fields in the returned result set to help identify the problem. If the session is in the running result set but you are unhappy with the performance it is likely the T-SQL needs to be optimized to make it run faster. This is a very broad topic and there are tons of articles and guides on the internet dealing with it.
  • blocking_session_id : If another session is blocking yours from executing, e.g. it has locked a table your command needs to write to, then this field will include the Id of the session causing the table to be locked. You can use EXEC sp_who2 to assess if the underlying command/query is experiencing a problem. If you are familiar with the blocking session you may know that you are able to kill the session without incurring any negative consequences. You can use the following code snippet to kill the blocking session.
    KILL blocking_session_id /*replace by the actual Id*/

    NOTE: Before you kill anything if it’s a command that has been running for a very long time it will likely take at least the same amount of time to roll back and unlock the table. You might be better off waiting for the session to finish on its own.

  • wait_type : If no blocking session is available, then the query is waiting for something, e.g. server resources etc. More details about wait types can be found HERE
  • wait_time : This stat value is measured in milliseconds. Short wait times are fine, specially in PAGEIOLATCH wait types (access to physical files) but longer wait times indicate a more serious problem.
  • last_wait_type : Indicates if the last wait type was different. This is quite helpful in analyzing if the query was blocked for the same reason before.

 

How to rename and/or remove tables in SQL Server with T-Sql generated by Excel formulas

This post deals with using an Excel file to generate T-Sql code to rename and/or remove tables given a scenario like the following. (To generate T-Sql to remove tables using T-sql see this post.)

Say someone sends you a list via an email or text file of tables they want renamed or removed from a database . You could go into SSMS object explorer and rename or delete each table in the list one by one. Or you could write the T-Sql statements individually but chances are you can speed things up using Excel.

With Excel you can input the schema and table name into a given cell and the T-Sql code will be generated to rename and drop the table using formulas.

To do this you can just download the Excel file template here. Download

Rename And Drop Script Generator

The template is setup assuming you are intending on the dropping the table sometime in the future but first you will be renaming it.

A good approach for removing objects is to rename the objects first. This makes it easier to put the environment back the way it was if there are any problems encountered. After a set period of time if there is no negative impact on the overall environment you can script out the object then drop it. (Obviously do this in a test environment first if possible)

To aid further in a cleanup project the Excel file also acts as a form that can be used to track progress as it contains the columns RenameDate, RestoreDate and DropDate. It also contains the column RestoreOriginalName. This column holds the formula to create the T-Sql code to renamed the tables back if there are any problems encountered.

You can adjust the formula in cell D2 to somethings other than _DELETE_ if you want to change the prefix so the tables will be renamed something else. If you just want to remove the tables you’ll have to run the script from column D before you can drop the tables using the script from column F.

Remember to drag the formula down for as many table entries as you have and it will generate the T-Sql needed.

You can create the Excel file manually yourself without downloading it.

To do so open a new Excel file and in an empty sheet name the first 9 columns as below:

A1: DatabaseName
B1: SchemaName
C1: TableName
D1: RenameForDeletion
E1: RestoreOriginalName
F1: DropTable
G1: RenameDate
H1: RestoreDate
I1: DropDate

For D2 enter the following:

=”USE [“&A2&”]; IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ‘”&B2&”‘ AND TABLE_NAME = ‘”&C2&”‘)) BEGIN exec sp_rename ‘”&B2&”.”&C2&”‘, ‘_DELETE_”&C2&”‘ END ELSE BEGIN SELECT ‘TABLE [“&A2&”].[“&B2&”].[“&C2&”] DOES NOT EXIST’ AS [RenameFailed] END;”

For E2 enter the following:

=”USE [“&A2&”]; IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ‘”&B2&”‘ AND TABLE_NAME = ‘_DELETE_”&C2&”‘)) BEGIN exec sp_rename ‘”&B2&”._DELETE_”&C2&”‘, ‘”&C2&”‘ END ELSE BEGIN SELECT ‘TABLE [“&A2&”].[“&B2&”].[“&C2&”] DOES NOT EXIST’ AS [RenameFailed] END;”

For F2 enter the following:

=”USE [“&A2&”]; IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ‘”&B2&”‘ AND TABLE_NAME = ‘_DELETE_”&C2&”‘)) BEGIN DROP TABLE [“&B2&”].[_DELETE_”&C2&”] END;”

To test that the scripts generated work you can create the mock database and table using the script below. The Excel file is loaded with these values by default.

CREATE DATABASE [TidBytez];
GO

USE [TidBytez]
GO

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Customer] ([ID] [int] NULL) ON [PRIMARY]
GO

 

How to tell if you are a member of a SQL Server group or create a list of group members using T-SQL

The following scripts will help you determine if you are a member of a group or role or create a list of group members in SQL Server without having to use SQL Server Management Studio. This is a particularly handy script in determining who might have access to the server through Active Directory groups.

/*
The code below indicates whether the current user is a member 
of the specified Microsoft Windows group or SQL Server database role.
A result of 1 = yes
,0 = no
,null = the group or role queried is not valid.
*/

SELECT IS_MEMBER('[group or role]')


/*
The code below will create a list of all the logins that are members 
of a group.
*/

EXEC master..xp_logininfo 
@acctname = '[group]',
@option = 'members'

 

How to get the default error log path for SQL Server with T-SQL

Below is a script to get the default error log path for SQL Server and set it as a variable. 

USE MASTER;
GO

DECLARE @LogPath AS VARCHAR(MAX)
DECLARE @ErrorLogPath TABLE (
	LogDate DATETIME
	,ProcessInfo VARCHAR(255)
	,PathText VARCHAR(MAX)
	);

INSERT INTO @ErrorLogPath
EXEC xp_readerrorlog 0
	,1
	,N'Logging SQL Server messages in file';

SET @LogPath = (
		SELECT REPLACE(REPLACE(REPLACE(PathText, 'Logging SQL Server messages in file ', ''), '''', ''), 'ERRORLOG.', '')
		FROM @ErrorLogPath
		);

SELECT @LogPath AS DefaultLogPath;
GO