37
Chapter 3: Installing SQL Server
3
Downgrading Between SQL Server Editions
Suppose a new corporate IT licensing policy mandates that all middle-tiered database appli-
cations need to be SQL Server Standard Edition, in which case you may fi nd yourself need-
ing to downgrade an existing Enterprise Edition of SQL Server to the Standard Edition.Downgrading from a higher-tier SQL Server 2012 edition to a lower-tier SQL Server edition,
such as from the Enterprise Edition to the Standard Edition, is only possible by perform-
ing an uninstallation of SQL Server. The process requires you to install the lower-tier SQL
Server edition after you uninstall the higher-tier SQL Server Edition.You can re-attach or restore user databases from a database backup to the lower-tier SQL
Server edition. User databases with higher-tier SQL Server edition specifi c features enabled
cannot be attached or restored to a lower-tier SQL Server edition. For example, a database
created in SQL Server 2012 Enterprise Edition that uses Enterprise Edition features, such as
Table Partitioning or Transparent Data Encryption (TDE), cannot be restored or attached to
the SQL Server 2012 Standard Edition without fi rst disabling these edition-specifi c features.To fi nd out edition-specifi c features applied to a database, you can query the dynamic
management view [sys].[dm_db_persisted_sku_features]. For example, the fol-
lowing T-SQL script queries edition-specifi c features applied to the SQL Server 2012
AdventureWorks2012 database:SELECT [feature_name]
FROM [AdventureWorks2012].[sys].[dm_db_persisted_sku_features]The [sys].[dm_db_persisted_sku_features] dynamic management view may return
rows containing any of the following Enterprise or Developer Edition features:■ (^) Compression
■ (^) Partitioning
■ (^) Transparent Data Encryption
■ (^) Change Capture
If no edition-specifi c features have been enabled in the user database, the [sys].[dm_
db_persisted_sku_features] dynamic management view does not return any rows.
Downgrading Between SQL Server Versions
In some cases you may need to downgrade between a newer version of SQL Server back to
a previous version. For example, a SQL Server version upgrade of an application’s back-end
database instance may have exposed bugs in the application that now force you to down-
grade back to the previous SQL Server version.
You can downgrade from SQL Server 2012 to previous versions of SQL Server by following
the same uninstallation process as previously mentioned. On the other hand, you can no
longer attach or restore user databases created or attached to an older version of SQL Server
to a SQL Server 2012 instance.
c03.indd 37c03.indd 37 7/30/2012 4:09:59 PM7/30/2012 4:09:59 PM
http://www.it-ebooks.info