using data.sqlclient;

sqlconnection cn;

cn=new sqlconnectin("user id=sa;database=pubs;data 
source=server");
cn.open();

system.data.oledb

dim oledb as new oledbconnection
oledbconnection1.open()
dim com as new oledbcommand("select empname from emp where 
empid=100".oledbconnection)
dim dr as oledbdatareader=com.executereader()
if dr.read() then
textbox1.text=dr(0)
end if

SQLConnection conn = new
SQLConnection("DataSource=;InitialCatalog=;User Id=;Password=");
SQLCommand cmd=new SQLCommand("select * from tablename",conn);
DataAdapter da=new DataAdapter(cmd);
Dataset ds=new Dataset();
da.fill(ds,"tablename");