string sqlstr = "Data Source=(local);Initial Catalog=web;Persist Security Info=True;User ID=sa;Password=8212";
            SqlConnection con = new SqlConnection(sqlstr);
            con.Open();
            string comstr = "select * from user where username='" + TextBox1.Text + "' and pwd='" + TextBox2.Text + "'";
            SqlCommand com = new SqlCommand(comstr, con);
             SqlDataReader dr = com.ExecuteReader();
帮我看看有什么问题？
是sql sever没装好吗？还是我没有写好

你遇到什么问题了？

解决了
"select * from user where username='" + TextBox1.Text + "' and pwd='" + TextBox2.Text + "'";
改为
"select * from [user] where username='" + TextBox1.Text + "' and pwd='" + TextBox2.Text + "'";

一般不要用系统保留的字段....
不过我建字段的时候，如果是系统保留的字段，他会自动加上"[]"....