事先閱讀

http://www.w3school.com.cn/sql/sql_union.asp

表1：

CREATE TABLE `A` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `orderno` bigint(20) DEFAULT NULL ，
  `userid` varchar(255) DEFAULT NULL,
  `resultid` tinyint(11) DEFAULT NULL,
  `remark` varchar(255) DEFAULT NULL,
  `createtime` datetime DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
  `role` int(1) DEFAULT NULL ,
  `nickname` varchar(20) DEFAULT NULL,
  `headimgurl` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=756 DEFAULT CHARSET=utf8;

表2：

CREATE TABLE `B` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `orderno` bigint(20) NOT NULL ,
  `payamount` decimal(12,2) DEFAULT NULL，
  `createdat` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ,
  `checkuserid` varchar(32) NOT NULL ,
  `picurls` text ,
  `status` tinyint(2) NOT NULL ,
  `productid` varchar(32) DEFAULT NULL,
  `checktype` tinyint(2) NOT NULL,
  `detail` varchar(255) DEFAULT NULL,
  `newuserid` int(11) NOT NULL,
  `nickname` varchar(200) DEFAULT NULL,
  `mobile` varchar(32) DEFAULT NULL ,
  `productname` varchar(255) DEFAULT NULL,
  `remark` varchar(255) DEFAULT NULL ,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=30 DEFAULT CHARSET=utf8;

需求：

1.獲取兩張表的orderno

2.按時間排序

2.區分是從哪張表中獲取的orderno

3.時間限定在3個月內，

4.進行分頁。

sql

        SELECT orderno,resource from 
        (select DISTINCT orderno,createtime as time,1 as resource
        from A where userid =666
        UNION
        SELECT orderno,createdat as time,0 as resource
        from B where checkuserid = 666)
        as a where time>=DATE_SUB(SYSDATE(),INTERVAL 3 MONTH) ORDER BY time DESC LIMIT 0,20
 

解釋