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Default Databases


Introduction



When you install Microsoft SQL Server, it also installs 4 databases named master, model, msdb, and tempdb. These databases will be for internal use. This means that you should avoid directly using them, unless you know exactly what you are doing.

The System Databases



One of the databases installed with Microsoft SQL Server is named master. This database holds all the information about the server on which your MS SQL Server is installed. For example, we saw earlier that, to perform any operation on the server, you must login. The master database identifies any person, called a user, who accesses the database, about when and how.

Besides identifying who accesses the system, the master database also keeps track of everything you do on the server, including creating and managing databases.

You should not play with the master database; otherwise you may corrupt the system. For example, if the master database is not functioning right, the system would not work.

Database Creation With Code


Introduction



The command used to create a database in SQL uses the following formula:

CREATE DATABASE DatabaseName
To assist you with writing code, in the previous lessons, we saw that you could use the query window.

The CREATE DATABASE (remember that SQL is not case-sensitive) expression is required. The DatabaseName factor is the name that the new database will have. Although SQL is not case-sensitive, you should make it a habit to be aware of the cases you use to name your objects. Every statement in SQL can be terminated with a semi-colon. Although this is a requirement in many implementations of SQL, in Microsoft SQL Server, you can omit the semi-colon. Otherwise, the above formula would be

CREATE DATABASE DatabaseName;
Here is an example:

CREATE DATABASE NationalCensus;
This formula is used if you do not want to provide any option. We saw previously that a database has one or more files and we saw where they are located by defauft. We also saw that you could specify the location of files if you want. To specify where the primary file of the database will be located, you can use the following formula:

CREATE DATABASE DatabaseName
ON PRIMARY
( NAME = LogicalName, FILENAME = Path )
The only three factors whose values need to be changed from this formula are the database name that we saw already, the logical name, and the path name. The logical name can be any one-word name but should be different from the database name. The path is the directory location of the file. This path ends with a name for the file with the extension .mdf. The path should be complete and included in single-quotes. Here is an example:

CREATE DATABASE NationalCensus
ON PRIMARY
( NAME = DataRepository, FILENAME = 'C:\Exercises\NationalCensus.mdf')
GO
Besides the primary file, you may want to create and store a log file. To specify where the log file of the database would be located, you can use the following formula:

CREATE DATABASE DatabaseName
ON PRIMARY
( NAME = LogicalName, FILENAME = Path.mdf )
LOG ON
( NAME = LogicalName, FILENAME = Path.ldf )
The new factor in this formula is the path of the log file. Like the primary file, the log file must be named (with a logical name). The path ends with a file name whose extension is .ldf. Here is an example:

CREATE DATABASE NationalCensus
ON PRIMARY
( NAME = DataRepository, FILENAME = 'C:\Exercises\NationalCensus.mdf')
LOG ON
( NAME = DataLog, FILENAME = 'C:\Exercises\NationalCensus.ldf')
GO





source : http://blogs.msdn.com/sharepoint/default.aspx