What's Meant by Sql Server database primary data file?

Question

When I create database with default size and default path I can't differentiate between its files  When I Go to the path of files of a database I find two files  for example the first one name is School.mdf and the second one name is School_log.ldf  I want to understand what's the difference between School.mdf and School_log.ldf ?  What's meant by Sql server database primary data file and Sql Server database transaction log file? thank you very much!

Jignesh Trivedi · Answer

hi MDF: Master Data File The .mdf is the data files of the database where all of the tables indexes (other than fulltext catalogs) stored procedures etc. are stored. The .mdf is the primary data file LDF: Log Data File The ldf is the transaction log. The transaction log is where all transactions are wirtten to. hope this will help you

Abhay Shanker · Answer

The .mdf and .ndf are the data files of the database where all of the tables indexes (other than fulltext catalogs) stored procedures etc. are stored. The .mdf is the primary data file and the .ndf only exists if a new file group is created. The ldf is the transaction log . The transaction log is where all transactions are wirtten to. Upon a checkpoint the contents of the transaction log .ldf is written to the appropriate .mdf and/or .ndf.

Vulpes · Answer

This link should answer all these questions for you: http://technet.microsoft.com/en-us/library/ms189563.aspx