what is sql server compact edition database file
SQL Server Compact SQL CE databases reside in a single .sdf file,[12] which can be up to 4 GB in size.[4] The .sdf file can be encrypted with 128-bit encryption for data security.[12] 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.[6] 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.[citation needed]
COM file A COM file is a type of simple executable file. On the Digital Equipment operating systems of the 1970s, .COM was used as a filename extension for text files containing commands to be issued to the operating system (similar to a batch file).[1] With the introduction of CP/M (a microcomputer operating system), the type of files commonly associated with COM extension changed to that of executable files. This convention was later carried over to MS-DOS. Even when complemented by the more general .exe file format for executables, the compact COM files remained viable and frequently used in MS-DOS.