Contained Databases in SQL Server 2012
Contained databases are a new feature in SQL Server 2012 and are defined on MSDN Library as ”a database that is isolated from other databases and from the instance of SQL Server that hosts the database”.
The containment setting of a database can be NONE, PARTIAL or FULL. But only NONE and PARTIAL are supported on SQL Server 2012.
There are three types of containment hinted at in SQL Server 2012:
- NONE: This default containment mode is what exists prior to SQL Server 2012. There are no boundaries defined or visible.
- PARTIAL: With partially contained databases, you have the ability to define clearer boundaries between databases and the server, making it easier for metadata to be hosted within the databases. This, in turn, makes SQL Server databases more portable and less dependent on underlying hosts.
- FULL:
Fully
contained
databases
are
only
alluded
to
in
SQL
Server
2012
BOL
in
a
few
locations
and
aren't
currently
available
as
an
option.
It's
assumed,
however,
that
full
containment
will
enable
greater
database
portability
and
potentially
allow
for
strict
enforcement
of
containment
boundaries
as
a
means
of
fully
isolating
databases
from
each
other
and
from
the
underlying
host.
Benefits and characteristics.
The following are some of the benefits and characteristics that contained databases have:
1. They make easier to migrate databases from one server to another. Errors related to orphan users are no longer an issue with contained databases, since a contained database user can now be created without an associated login.
2. Authentication can now occur at the database level.
3. Contained database users can be Windows and SQL Server authentication users.
4. A contained database user can access only contained database objects. They cannot access system databases and cannot access server objects.
5. Metadata is stored on the contained database and not stored on system databases. This makes contained databases more portable than the databases we know.
Disadvantages
and
limitations.
Some disadvantages and limitations are the following:
1. There are some security concerns. A database owner can create contained database users without the permission of a DBA. The possibility of denial of service attacks exist with contained databases using AUTO_CLOSE option. For security best practices about contained databases, please see the references shown at the end of the article.2. Partially contained databases cannot use replication, change data capture, change tracking, numbered procedures, schema-bound objects that depend on built-in functions with collation changes. You may find more limitations on the references shown at the end of this article.Requirements of contained databases.
1
It
is
required
to
enable
contained
databases
on
the
instance.2. The
contained
database
needs
to
be
added
to
the
connection
string
or
specified
when
connecting
via
SQL
Server
Management
Studio.Step-by-step
instructions
on
how
to
create
a
contained
database.
To be able to create contained databases on a SQL Server 2012 instance, we need to enable the contained database authentication option on the instance.
Open SQL Server 2012 Management Studio, connect to the instance, make a right click on the name of the instance on Object Explorer, select the Advanced page on the "Select a page" panel, and set to true the "Enable Contained Databases" option.
Alternatively, you can use sp_configure system stored procedure to enable contained databases on the instance, as shown below.
Some disadvantages and limitations are the following:
1. There are some security concerns. A database owner can create contained database users without the permission of a DBA. The possibility of denial of service attacks exist with contained databases using AUTO_CLOSE option. For security best practices about contained databases, please see the references shown at the end of the article.2. Partially contained databases cannot use replication, change data capture, change tracking, numbered procedures, schema-bound objects that depend on built-in functions with collation changes. You may find more limitations on the references shown at the end of this article.Requirements of contained databases.
1
It
is
required
to
enable
contained
databases
on
the
instance.2. The
contained
database
needs
to
be
added
to
the
connection
string
or
specified
when
connecting
via
SQL
Server
Management
Studio.Step-by-step
instructions
on
how
to
create
a
contained
database.To be able to create contained databases on a SQL Server 2012 instance, we need to enable the contained database authentication option on the instance.
Open SQL Server 2012 Management Studio, connect to the instance, make a right click on the name of the instance on Object Explorer, select the Advanced page on the "Select a page" panel, and set to true the "Enable Contained Databases" option.
Alternatively, you can use sp_configure system stored procedure to enable contained databases on the instance, as shown below.
EXEC
sp_configure
'show
advanced',
1
GO
RECONFIGURE
GO
GO
RECONFIGURE
GO
EXEC
sp_configure
'contained
database
authentication',
1GO
RECONFIGURE
GO
RECONFIGURE
GO
When a database is created the "Containment type" should be set to "partial" to make the database a contained database, as shown below.
This can be done using T-SQL too, as shown below.
A contained database allows the creation of a database user that is not associated to an instance login. A contained database user can be created expanding the Security folder on the contained database, making a right click on the Users folder and selecting the "New User" option.
Next, set the user type to "SQL user with password", assign a user name, set the password for the database user and specify the default schema for the user.
Specify the roles for this user on the database and click OK.
If you would like to create the contained database user using T-SQL, please see the example below.CREATE USER [MorilloCD2User]
WITH PASSWORD=N'p@ssw0rd123',
DEFAULT_SCHEMA=[dbo]GO
To connect a contained database user to a contained database, the database name should be specified on the connection string. If you are using SQL Server Management Studio, on the Connect to Server dialog specify the authentication, specify the user name, provide the password, click on the Options button and specify the database name on the "Connect to database" combo box.
