SP in Fundamental level

SP in Fundamental level:

SP_RENAMEDB: Here SP stands for Stored Procedure. This stored procedure is used to change the name of the existing database.

Syntax: SP_RENAMEDB ‘OLD DATABASENAME’, ‘NEW DATABASENAME’

            E.g.: SP_RENAMEDB  ‘NRSTT’, ‘NRSTTS’

The above statement renames (changes the database name) NRSTT to NRSTTS

SP_RENAME: This stored procedure is used for changing the name of the table and for changing the name of the column

i. Syntax to change the name of the table

SP_RENAME ‘OLD TABLENAME’, ‘NEW TABLENAME’

E.g.      SP_RENAME ‘EMP’, ‘EMPLOY’

The above stored procedure changes the name of EMP table to EMPLOY

ii. Syntax to change the name of the column

SP_RENAME ‘TABLE.OLDCOLUMN NAME’, ‘NEW COLUMNNAME’

E.g.      SP_RENAME ‘STUDENT.ADR’, ‘ADDRESS’

The above stored procedure changes the name of ADR column to ADDRESS in STUDENT table.

SP_HELP: This stored procedure is used to display the description of a specific table.

Syntax: SP_HELP TABLENAME

E.g.: SP_HELP EMP

The above stored procedure displays the description of EMP table

SP_DATADASES: This Stored procedure displays the list of databases available in SQL Server.

Syntax: SP_DATABASES

SP_TABLES: This stored procedure displays the list of tables available in the current database.

Syntax: SP_TABLES

SP_HELPDB: This stored procedure is used to display the description of  master and log data file information of a specific database

Syntax: SP_HELPDB Database-Name

Ex: SP_HELPDB SAMPLE

SP_SPACEUSED: This stored procedure is used to find the memory status of the current database

Syntax: SP_SPACEUSED

Collation levels and default collation

Collation levels and default collation:

Collation can be set at 4 levels in SQL Server:
1.       Server
2.       Database
3.       Columns
4.       Expression

But collations are compared either at columns level or in expressions. So I am starting from lower to upper levels. The collations of upper two levels (server and database) are only helpful in providing default collation to columns and expressions.
Expression collation: All literals, variables and parameters and functions without any input parameters, by default get the collation of database.

Column collation: When we create a table we can specify a collation explicitly for all character data type (char, nchar, varchar, nvarchar, text, ntext) columns. If not specified then collation of database would be the default collation of a column. The collation of a column can be changed by using an ALTER TABLE statement similar to the following:

ALTER TABLE TestTab ALTER COLUMN CharCol CHAR(10) COLLATE Greek_CS_AI

Database collation: When we create a new database we can specify collation. If not specify then collation of model database is assigned as default collation. To know the collation of database use below statement:

SELECT DATABASEPROPERTYEX('testDB', 'Collation') SQLCollation

Database collation can be changed using the ALTER DATABASE statement as below.:

ALTER DATABASE myDB COLLATE Greek_CS_AI

When collation of database is changed it does not automatically change the collation of all columns of all tables. But the new collation would be the default collation for new columns created hence forth and for expressions.

Server collation: This is set during SQL Server installation. It’s the default collation for system databases. Because this is the collation of model database so this would be the default collation for all new databases that would be created on this server. The server collation can not be changed. To query the server collation use the below statement:

SELECT CONVERT (varchar, SERVERPROPERTY('collation'))

Executing a SQL statement from command prompt:

Executing a SQL statement from command prompt:

Sometimes we need to execute some –T-SQL script from command prompt. This is a common requirement when some t-sql scripts are needed to be scheduled by windows scheduler.

Here I will explain how we can execute T-SQL script from command prompt. Below I created an executable file (.bat) to create a backup of AdventureWorks database so that I can schedule this executable using Windows scheduler.

 Create a text file for example c:\sql.txt and write below backup script in it:

USE master

GO

BACKUP DATABASE AdventureWorks

TO DISK = 'D:\SQL_Backup\AdventureWorks.bak' WITH INIT

Create another batch file for example Backup.bat and write the below statement inside it:

sqlcmd -S ServerName -U yourLogin -P yourPassowrd -i c:\sql.txt

Now we can execute this Backup.bat file from command prompt or can schedule using windows scheduler. Thus we have scheduled a task that is not dependent on SQL server Agent service.

Find who dropped, created or altered the table, SP or any object

Find who dropped, created or altered the table, SP or any object

If any database object is dropped, created or altered accidentally, sometimes you may need information about:

Who dropped, created or altered the object? When culprit not accept the mistake.

When the object was dropped, created or altered? Especially drop time of table is required for point in time recovery from database backups.

These changes are not recorded in SQL Server Error Log but are recorded in default trace. If you have not disabled the default trace and started looking into the issue soon after change occurred you could get this information. The path of trace file is “C:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\Log\”. The folder MSSQL10.SQLEXPRESS may be different according to your SQL Server instance name. Here you would find 5 profiler trace files named as “log_1”, “Log_2”, etc. The file number is increased by time (in following example I used “log_16.trc”). Find the file that is most recently modified and use the below t-sql query to open that file:

SELECT ObjectName, DatabaseName, StartTime, NTDomainName, HostName, NTUserName, LoginName

FROM fn_trace_gettable('C:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\Log\log_16.trc', default)

WHERE objectname is not null  

You can start a trace as default in two ways:

1. create a stored procedure that starts a trace# and then set that SP as startup as following:

CREATE PROC sp_StartTrace
AS
DBCC TRACEON (1204) 
GO

sp_procoption sp_StartTrace , 'STARTUP', 'ON'

2. Start SQL Server at Run window using NET START command with -T switch as below:
net start SQLSERVER -T 1204

SQL Server System Databases

SQL Server System Databases

• Master
• Purpose - Core system database to manage the SQL Server instance.  In SQL Server, the Master database is the logical repository for the system objects residing in the sys schema.  In SQL Server 2000 and previous editions of SQL Server, the Master database physically stored all of the system objects.
• Prominent Functionality
• Per instance configurations
• Databases residing on the instance
• Logins
• Linked\Remote servers
• Endpoints
• Additional Information
• The first database in the SQL Server startup process
• In SQL Server 2005, needs to reside in the same directory as the Resource database
• Resource
• Purpose - The Resource database is responsible for physically storing all of the SQL Server 2005 system objects. This database has been created to improve the upgrade and rollback of SQL Server system objects with the ability to overwrite only this database.
• Introduced in SQL Server 2005 to help manage the upgrade and rollback of system objects
• Prior to SQL Server 2005 the system related data was stored in the master database
• Read-only database that is not accessible via the SQL Server 2005 tool set
• The database ID for the Resource database is 32767
• The Resource database does not have an entry in master.sys.databases
• TempDB
• Purpose - Temporary database to store temporary tables (#temptable or ##temptable), table variables, cursors, work tables, row versioning, create or rebuild indexes sorted in TempDB, etc. Each time the SQL Server instance is restarted all objects in this database are destroyed, so permanent objects cannot be created in this database.
• Each time a SQL Server instance is rebooted, the TempDB database is reset to its original state
• Model
• Purpose - Template database for all user defined databases
• Additional Information
• User defined tables, stored procedures, user defined data types, etc can be created in the Model database and will exist in all future user defined databases
• The database configurations such as the recovery model for the Model database are applied to future user defined databases
• MSDB
• Purpose - Primary database to manage the SQL Server Agent configurations
• Prominent Functionality
• SQL Server Agent Jobs, Operators and Alerts
• SSIS Package storage in SQL Server 2005,2008r2 and 2012
• Additional Information
• Provides some of the configurations for the SQL Server Agent service.
• Distribution
• Purpose - Primary data to support SQL Server replication
• Prominent Functionality
• Database responsible for the replication meta data
• Supports the data for transaction replication between the publisher and subscriber(s)
•  
• ReportServer
• Purpose - Primary database for Reporting Services to store the meta data and object definitions
• ReportServerTempDB
• Purpose - Temporary storage for Reporting Services
• Prominent Functionality