Describe the various types of files that can be created in SQL Server databases.

At a minimum, every SQL Server database has two operating system files i.e. a data file and a log file. Data files contain data and objects such as tables, indexes, stored procedures, and views. Log files contain the information that is required to recover all transactions in the database. Data files can be grouped together in file groups for allocation and administration purposes. SQL Server databases have three types of files, as shown in the following table. File Description Primary The primary data file contains the startup information for the database and points to the other files in the database. User data and objects can be stored in this file or in secondary data files. Every database has one primary data file. Secondary Secondary data files are optional, are user-defined, and store user data. Secondary files can be used to spread data across multiple disks by putting each file on a different disk drive. Additionally, if a database exceeds the maximum size for a single Windows file, you can use secondary data files so the database can continue to grow. Transaction Log The transaction log files hold the log information that is used to recover the database. There must be at least one log file for each database.