Sql server® 2012 t-sql fundamentals

File extensions .mdf, .ldf, and .ndf

The database file extensions .mdf and .ldf are quite straightforward. The extension .mdf 

stands for Master Data File (not to be confused with the master database), and .ldf stands 

for Log Data File. According to one anecdote, when discussing the extension for the sec-

ondary data files, one of the developers suggested, humorously, using .ndf to represent 

“Not Master Data File,” and the idea was accepted.

Schemas and Objects

When I said earlier that a database is a container of objects, I simplified things a bit. As illustrated in 

Figure 1-8, a database contains schemas, and schemas contain objects. You can think of a schema as a 

container of objects such as tables, views, stored procedures, and others. 

dbo

Sales

HR

User Database

Schema

Objects

FIGuRE 1-8

  A database, schemas, and database objects. 

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