Mysql中使用Union—多表合并之行合并

这篇文章主要介绍了Mysql中使用Union—多表合并之行合并,如果我们需要将两个select语句的结果作为一个整体显示出来，我们就需要用到union或者unionall关键字,union(或称为联合)的作用是将多个结果合并在一起显示出来,需要的朋友可以参考下

Union (all)语句格式

select 列名 from 表A

union （all）

select 列名 from 表B

注意事项：

合并的表的列数必须是一致的，也就是表的列数要相同union 与union all 对两个查询结果合并的时候，如果结果有重复，union 会把重复的值删除；union 与union all不能与order by同时使用，如果要对结果进行排序，可以用子查询

案例解析

统计20170703—20170709周内每天及本周累计销售金额、订单量、会员数、订单占比

统计时间段内每天的累计销售金额、订单量、会员数统计本周累计销售金额、订单量、会员数订单占比union合并表对比 union all合并表——因为没有重复数据，所以两表合并结果一样

-- 1、统计时间段内每天的累计销售金额、订单量、会员数SELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/      ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/      ,COUNT(DISTINCT dimMemberID) num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W') ;-- 2、统计本周累计销售金额、订单量、会员数SELECT SUM(AMT) as total_money      ,COUNT(DISTINCT salesID) as total_num_order      ,COUNT(DISTINCT dimMemberID) total_num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0;-- 3、订单占比SELECT DATE_FORMAT(dimDateID,'%W') AS week_1      ,CONCAT(ROUND( COUNT(DISTINCT salesID)/(SELECT COUNT(DISTINCT salesID)                                FROM dw.fct_sales                                where dimDateID between '20170703' and '20170709'                                and dimMemberID <>0),4)*100,'%') as order_rateFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W') ;-- 4、union合并表SELECT DATE_FORMAT(dimDateID,'%W') AS week_1       ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order      ,COUNT(DISTINCT dimMemberID) num_member      ,CONCAT(ROUND( COUNT(DISTINCT salesID)/(       SELECT COUNT(DISTINCT salesID)       FROM dw.fct_sales       where dimDateID between '20170703' and '20170709'       and dimMemberID <>0),4)*100,'%') as order_rateFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W')UNION SELECT week(dimDateID,1)               /*为了保证列数一样，week返回日期为一年中的第几周 weel(date,1):从周一开始为第一天*/      ,SUM(AMT) as total_money      ,COUNT(DISTINCT salesID) as total_num_order      ,COUNT(DISTINCT dimMemberID) total_num_member      ,'100%' as total                 /*为确保列数一样*/FROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by week(dimDateID,1);            /*出现汇总函数需要进行分组*/-- 5、对比 union all合并表——因为没有重复数据，所以两表合并结果一样SELECT DATE_FORMAT(dimDateID,'%W') AS week_1       ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order      ,COUNT(DISTINCT dimMemberID) num_member      ,CONCAT(ROUND( COUNT(DISTINCT salesID)/(       SELECT COUNT(DISTINCT salesID)       FROM dw.fct_sales       where dimDateID between '20170703' and '20170709'       and dimMemberID <>0),4)*100,'%') as order_rateFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W')UNION ALL SELECT week(dimDateID,1)               /*为了保证列数一样，week返回日期为一年中的第几周 weel(date,1):从周一开始为第一天*/      ,SUM(AMT) as total_money      ,COUNT(DISTINCT salesID) as total_num_order      ,COUNT(DISTINCT dimMemberID) total_num_member      ,'100%' as total                 /*为确保列数一样*/FROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by week(dimDateID,1);            /*出现汇总函数需要进行分组*/

区分union 和 union all ，利用重复数据对比，合并两个一模一样的表

-- unionSELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/      ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/      ,COUNT(DISTINCT dimMemberID) num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W')UNION SELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/      ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/      ,COUNT(DISTINCT dimMemberID) num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W') ;-- union allSELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/      ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/      ,COUNT(DISTINCT dimMemberID) num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W')UNION ALL SELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/      ,SUM(AMT) as money      ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/      ,COUNT(DISTINCT dimMemberID) num_memberFROM dw.fct_saleswhere dimDateID between '20170703' and '20170709'and dimMemberID <>0group by DATE_FORMAT(dimDateID,'%W') ;

多表合并中的排序问题 order by——把合并后的表作为一个临时表，再进行排序

注意临时表需要命名

排序要对新的列名进行排序

SELECT sn.*FROM (      SELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/            ,SUM(AMT) as money             ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/            ,COUNT(DISTINCT dimMemberID) num_member      FROM dw.fct_sales      where dimDateID between '20170703' and '20170709'      and dimMemberID <>0      group by DATE_FORMAT(dimDateID,'%W')      UNION       SELECT DATE_FORMAT(dimDateID,'%W') as week_1      /*把时间转化为星期模式*/            ,SUM(AMT) as money             ,COUNT(DISTINCT salesID) as num_order       /*一个会员一周可以下多单，所以要统计会员数，需要去重*/            ,COUNT(DISTINCT dimMemberID) num_member      FROM dw.fct_sales      where dimDateID between '20170703' and '20170709'      and dimMemberID <>0      group by DATE_FORMAT(dimDateID,'%W') ) as snorder by money desc;                                    /*注意要对money排序，而不是SUM(AMT)*/-- order by SUM(AMT) desc;                              /*会报错，需要用临时表的列名，并且要对临时表取列名，否则也会报错*/

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