using System.Net; # region 获取内.外网Ip /// <summary> /// 获取本地ip地址,优先取内网ip /// </summary> public static String GetLocalIp() { String[] Ips = GetLocalIpAddress(); foreach (String ip in Ips) if (ip.StartsWith("10.80.")) return ip; foreach
1.左连接 select a.filed1,a.filed2,b.filed1 from a (左表) left join b(右表) on a.commonfiled = b.commonfiled 查询思路:按照匹配字段(外键),b表记录与a表记录进行逐一匹配,若有n条匹配,则形成n行.若无匹配,则左表中得记录是全的,即使右表没有匹配的字段存在 2.右连接 select a.filed1,a.filed2,b.filed1 from a (左表) right join b(右表) on a.