A summary
First clear SQLServer database system, a total of five: Master, Model, Msdb, Tempdb, Resource.
1, Master Database
(1) master database records all the system-level information, including metadata (login account), configuration settings, endpoints, linked servers and systems. Note that the system object not in the master database, while the resource library;
(2) mater database also records the location of all the presence of other databases, database files;
(3) master database is unavailable, the SQLServer instance will not start;
(4) can not be added to the master database file or group of files, you can not change the collation of the master database, the default collation of the instance;
(5) can not delete the master database, you can not remove the guest user
(6) can not create a trigger, you can not start the CDC (Change Data Capture), can not participate in database mirroring, can not be set to read-only, can not be set to OFFLINE (offline)
2, Model database
3, Msdb database
4, Tempdb database
5, Resource Database