SQL database: Key concepts

Learn more about the following database concepts.

What is a database?

A database is a collection of information, tables, and other objects organized and presented to serve a specific purpose such as searching, sorting, and recombining data. Databases are stored in files.

What is a data file?

A data file holds the data stored in the database. Every SQL Server database has at least one primary data file and can optionally have multiple secondary data files to hold data that does not fit on the primary data file.

What is a log file?

A log file is a file or set of files containing a record of the modifications made in a database.

What is a table?

A table is used to store data in a relational database. Each table stores information about one of the types of objects modeled by the database.

What is an index?

An index provides fast access to data in the rows of a table, based on key values.