Sql server® 2012 t-sql fundamentals

 

CHAPTER 1

 

Background to T-SQL Querying and Programming

 

 17

In terms of security, to be able to connect to a SQL Server instance, the database administrator 

(DBA) must create a logon for you. In an on-premises SQL Server instance, the logon can be tied to 

your Windows credentials, in which case it is called a Windows authenticated logon. With a Windows 

authenticated logon, you won’t need to provide logon and password information when connecting 

to SQL Server because you already provided those when you logged on to Windows. With both on-

premises SQL Server and SQL Database, the logon can be independent of your Windows credentials, 

in which case it is called a SQL Server authenticated logon. When connecting to SQL Server using a 

SQL Server authenticated logon, you will need to provide both a logon name and a password. 

The DBA needs to map your logon to a database user in each database that you are supposed to 

have access to. The database user is the entity that is granted permissions to objects in the database.

SQL Server 2012 supports a feature called contained databases that breaks the connection 

between a database user and a server-level logon. The user is fully contained within the specific 

database and is not tied to a logon at the server level. When creating the user, the DBA also provides 

a password. When connecting to SQL Server, the user needs to specify the database he or she is con-

necting to, as well as the user name and password, and the user cannot subsequently switch to other 

user databases.

So far, I’ve mainly mentioned the logical aspects of databases. If you’re using SQL Database, your 

only concern is that logical layer. You do not deal with the physical layout of the database data and 

log files, tempdb, and so on. But if you’re using on-premises SQL Server, you are responsible for the 

physical layer as well. Figure 1-7 shows a diagram of the physical database layout.

User

Database

Transaction

Log

.ldf

PRIMARY

Data

.mdf

Data

.mdf

Data

.mdf

FG1

Data

.mdf

Data

.mdf

FG2

Log File

Filegroup

Data File