C #. NET database operation notes

1. Database Connection
Store the connected database information in the following files to facilitate unified management.
Web. config // do not understand this yet. I think it is very useful to study it well. NET should use. NET.
<? Xml version = "1.0" encoding = "UTF-8"?>
<Configuration>
<ConfigSections>
<SectionGroup name = "system. web">
<Section name = "database" type = "System. Configuration. NameValueSectionHandler, System, Version = 1.0.5000.0, Culture = neutral, PublicKeyToken = b77a5c561934e089"/>
</SectionGroup>
</ConfigSections>

<System. web>
<! -- Too many threads have been transferred too many times
ASPX worker has