通过Windows身份验证来连接：
sqlconnection new sqlconnection.connectionstring = "Persist Security Info=False;Integrated Security=SSPI;database=northwind;server=mySQLServer"
通过SQL 中的 SA 用户验证来连接：
sqlconnection new sqlconnection.connectionstring＝"Persist Security Info=False;UId=sa;Pwd=xxx;database=northwind;server=mySQLServer"
通过 OLEDB 来连接：
oledbconnection.connectionstring = "Provider=SQLOLEDB;Data Source=localhost;Initial Catalog=Northwind;User id=sa;password=xxx"
