Question

Another question i asked..

Closing a conneciton in the "unload" method

Has piqued my interest in the subject. When relating to asp.net/c# I understand that there is an underlying expense in opening/closing database connections, I’m interested in whether it’s more expensive to either…

• Open DB connection at the start of a request
• Do several operations
• close connection at end or the request

vs

• Open connection directly before any database command
• Close straight away
  (thus opening and closing connections several time during a request)

If anyone could provide any insight, or point me in the direction of some reading material on the matter, that would be awesome.

Answer 1

You may find the following links useful. They point to Microsoft’s best practices implementing Data Access Layer:

1. Data Layer guidelines: http://msdn.microsoft.com/en-us/library/ee658127.aspx
2. Data Components design: http://msdn.microsoft.com/en-us/library/ee658119.aspx
3. About Connections specifically: http://msdn.microsoft.com/en-us/library/ee658127.aspx#Connections

I agree with Steve that, in most cases, you should keep connection open for the shortest time possible.

From my experience, I used to re-work code that was using opened connections for extended periods of time and that caused licensing problems (number of concurrent users).