SQL Server Compact

SQL CE databases can support ACID-compliance, but do not meet the durability requirement by default because AutoFlush buffers changes in memory (including enlisted ambient transactions and explicit SQL CE transactions that do not override the Commit() call with an CommitMode.Immediate value). Therefore, committed transaction changes can be lost. To meet the durability requirement the commit call on the transaction must specify the immediate flag. Like Microsoft SQL Server, SQL CE supports transactions, referential integrity constraints, locking as well as multiple connections to the database store. However, nested transactions are not supported, even though parallel transactions (on different tables) are. The current release does not support stored procedures or native XML data type either. It uses a subset of T-SQL for querying and due to lack of XML support, XQuery is not supported either. Queries are processed by an optimizing query processor. SQL CE databases also support indexing, as well as support remote data replication (local caching of data in remote databases) and merge replication (bidirectional synchronization with master databases).

SQL CE databases can be created and managed from Microsoft Visual Studio and some older versions of SQL Server Management Studio as well.

SQL CE databases reside in a single .sdf file, which can be up to 4 GB in size. The .sdf file can be encrypted with 128-bit encryption for data security. SQL CE runtime mediates concurrent multi-user access to the .sdf file. The .sdf file can simply be copied to the destination system for deployment, or be deployed through ClickOnce. SQL CE runtime has support for DataDirectories. Applications using an SQL CE database need not specify the entire path to an .sdf file in the ADO.NET connection string, rather it can be specified as |DataDirectory|\<database_name>.sdf, defining the data directory (where the .sdf database file resides) being defined in the assembly manifest for the application.

Setting a password for the database file is optional. The database can be compressed and repaired with the option of the compacted/repaired database to be placed into a new database file."SQL Server 2005 Compact Edition Datasheet". Archived from the original on 2007-03-16. Retrieved 2007-07-03.