Mysql的union
我同事写了一条Sql语句,当时没看明白,下面晒出来:
SELECT SUM(new_cart) as new_cart,SUM(new_collect) as new_collect, SUM(total_cart) as total_cart, SUM(total_collect) as total_collect, SUM(ipv) ipv, SUM(iuv) iuv FROM
( SELECT SUM(new_cart) as new_cart,SUM(new_collect) as new_collect, as total_cart, as total_collect, SUM(ipv) ipv, SUM(iuv) iuv FROM tablename WHERE id <= 5 union all SELECT as new_cart, as new_collect,total_cart, total_collect, AS ipv, AS iuv FROM tablename WHERE id = 5
) as t
ORDER BY new_cart desc;
数据表结构:
CREATE TABLE `tablename` (
`id` int() NOT NULL AUTO_INCREMENT,
`new_cart` bigint() DEFAULT NULL,
`new_collect` bigint() DEFAULT NULL,
`total_cart` bigint() DEFAULT NULL ,
`total_collect` bigint() DEFAULT NULL ,
`ipv` bigint() DEFAULT NULL ,
`iuv` bigint() DEFAULT NULL ,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
那么其实是使用了MYSQL的UNION。UNION:对两个结果集进行并集操作,不包括重复行,同时进行默认规则的排序;
录入语句:
mysql> insert into tablename values (,,,,,,);
Query OK, row affected (0.00 sec) mysql> insert into tablename values (,,,,,,);
Query OK, row affected (0.00 sec) mysql> insert into tablename values (,,,,,,);
Query OK, row affected (0.00 sec) mysql> insert into tablename values (,,,,,,);
Query OK, row affected (0.00 sec) mysql> insert into tablename values (,,,,,,);
Query OK, row affected (0.00 sec)
执行第一条语句:
SELECT SUM(new_cart) as new_cart,SUM(new_collect) as new_collect, as total_cart, as total_collect, SUM(ipv) ipv, SUM(iuv) iuv FROM tablename WHERE id <= union all SELECT as new_cart, as new_collect,total_cart, total_collect, AS ipv, AS iuv FROM tablename WHERE id = ;
输出:
+----------+-------------+------------+---------------+------+------+
| new_cart | new_collect | total_cart | total_collect | ipv | iuv |
+----------+-------------+------------+---------------+------+------+
| | | | | | |
| | | | | | |
+----------+-------------+------------+---------------+------+------+
rows in set (0.00 sec)
可见,union是把两条记录合并输出出来,那么再将这些内容相加输出该怎么办哪?聪明的你一定想到了第一条数据语句了吧~
mysql> SELECT SUM(new_cart) as new_cart,SUM(new_collect) as new_collect, SUM(total_cart) as total_cart, SUM(total_collect) as total_collect, SUM(ipv) ipv, SUM(iuv) iuv FROM ( SELECT SUM(new_cart) as new_cart,SUM(new_collect) as new_collect, as total_cart, as total_collect, SUM(ipv) ipv, SUM(iuv) iuv FROM tablename WHERE id <= union all SELECT as new_cart, as new_collect,total_cart, total_collect, AS ipv, AS iuv FROM tablename WHERE id = ) as t ORDER BY new_cart desc;
+----------+-------------+------------+---------------+------+------+
| new_cart | new_collect | total_cart | total_collect | ipv | iuv |
+----------+-------------+------------+---------------+------+------+
| | | | | | |
+----------+-------------+------------+---------------+------+------+
row in set (0.00 sec)
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