mysql交叉表的写法

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创建 2 张表一张 t_shuiguo 水果表一张 t_supermarket 超市表

现在我要查一个超市的各区水果价格的汇总

如下: 表 A

那么首先水果表是可以动态添加的所有 A 表中的列是动态的先不考虑

先看下静态的如果就是这么 4 个水果

那么 SQL 可以这么写 (参考了网上一些列子)

— 静态 sql

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select ifnull(groups, total) as groups,
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sum(if(name= 苹果 ,prices,0)) as 苹果 ,
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sum(if(name= 梨 ,prices,0)) as 梨 ,
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sum(if(name= 橘子 ,prices,0)) as 橘子 ,
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sum(if(name= 樱桃 ,prices,0)) as 樱桃 ,
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sum(if(name= total ,prices,0)) as totals
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from
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(select A.groups as groups,IFNULL(A.name, total) as name ,sum(A.price) as prices
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from
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(select
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m.groups as groups ,s.name as name,m.price as price
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from t_supermarket m
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inner join t_shuiguo s
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on m.shuiguo = s.id
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) A
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group by groups, name
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with rollup
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having groups is not null
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) B
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group by groups
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with rollup

然后比较费劲的就是动态的需要用到存储过程

如下：

001
— 定义存储过程结束符
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delimiter $$
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— 有先删除再创建过程
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drop procedure if exists searchShuiguo $$
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create procedure searchShuiguo()
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begin
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— 定义 sql 前端
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declare v_1 varchar(1000) default SELECTIFNULL(groups,\ total\) as groups
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— 定义 sql 后端
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declare v_2 varchar(1000) default from (select groups,IFNULL(code,\ total\) as code ,sum(A.price) as prices www.2cto.com
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from (
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selectm.groups as groups ,s.code as code,m.price as price
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from t_supermarket m inner join t_shuiguo s on m.shuiguo = s.id
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) A
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group by groups,
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code with rollup having groups is not null
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) B
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group by groups
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with rollup
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— 定义临时参数
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declare v_temp varchar(2000);
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— 定义要遍历的变量
044 www.2cto.com

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declare v_shuiguo varchar(100) ;
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— 定义结束变量
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declare stop int default 0;
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— 定义游标去查水果列表
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declare cur cursor for select code from t_shuiguo ;
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— 一个没找到的回调设置
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declare continue handler for not found set stop = 1;
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— 游标遍历拼接 sql 字符串
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OPEN cur;
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FETCH cur INTO v_shuiguo;
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WHILE stop = 0
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DO
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if v_temp = then
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set v_temp = CONCAT(v_1, sum(if(code =\ ,v_shuiguo, \
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set v_1 = CONCAT(v_temp, ,prices,0)) as ,v_shuiguo);
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else
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set v_temp =
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set v_temp = CONCAT(v_1, , , sum(if(code =\ ,v_shuiguo, \ ,
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set v_1 = CONCAT(v_temp, ,prices,0)) as ,v_shuiguo);
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end if;
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FETCH cur INTO v_shuiguo;
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END WHILE;
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CLOSE cur;
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set @v_result = CONCAT(v_1, , sum(if(code=\ total\ ,prices,0)) as \ total\
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set @v_result = CONCAT(@v_result,v_2);
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— 执行 sql
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prepare stmt from @v_result;
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EXECUTE stmt ;
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www.2cto.com
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deallocate prepare stmt;
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end $$
哦了

call searchShuiguo () 就可以了