连接数据库有关问题

连接数据库问题
string str_sqlconnection = "server=.\\SQLEXPRESS;Initial Catalog=XFGL;Integrated Security=false;uid=sa;pwd=789456;";
上面的样子能连接上，但是把.\\SQLEXPRESS改成127.0.0.1或者localhost就失败了，请问为什么？

[解决办法]
string str_sqlconnection = "server=127.0.0.1\\SQLEXPRESS;Initial Catalog=XFGL;Integrated Security=false;uid=sa;pwd=789456;";

而不是
string str_sqlconnection = "server=127.0.0.1;Initial Catalog=XFGL;Integrated Security=false;uid=sa;pwd=789456;";

[解决办法]