sql链接字符串
<add name="ConnectionString" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true"
providerName="System.Data.SqlClient" />
<add name="ConnectionString" connectionString="Data Source=(local);Initial Catalog=AdventureWorks; Integrated Security=SSPI; Database=aaaa"
providerName="System.Data.SqlClient" />
<add name="ConnectionString" connectionString="server=192.168.1.1;database=ddd;uid=sa;pwd=sa"
providerName="System.Data.SqlClient" />