Learn from errors

Tip:Whatever you are studying ,Study it with the help of search engines. For example if you are studying DetailsView in Asp.net then append DetailsView with ' Errors' and put in search engine .
to get the nuts and bolts of the funda

1)SQL Errors:
http://technet.microsoft.com/en-us/library/ms164014.aspx
2)ADO.net Errors:
http://www.kbalertz.com/technology_13_2.aspx
3)XML Errors:
http://www.perfectxml.com/DotNetXMLKBs.asp?t=P