MYSQL从逗号分隔的不同值计数

-1

如何从MySql中以逗号分隔值存储的数据中选择不同的值和相对计数？MYSQL从逗号分隔的不同值计数

这是在表中的数据看起来的样子：

"Category" "Values"  
"red"   "D,A,D,D"  
"yellow"  "A,A,D,D"

欲望输出：

"red" "D" "3"  
"red" "A" "1"  
"yellow" "D" "2"  
"yellow" "A" "2"

你能想到的在mysql中一个很好的办法让我好象路输出做了什么？提前致谢。

来源

2016-11-15 Gabriele Garufi

是的，我能想到的好方法是使桌子正常化并使其成为一对多，之后生活将变得简单。 –

http://stackoverflow.com/questions/3653462/is-storing-a-delimited-list-in-a-database-column-really-that-bad/3653574 – e4c5

使用派生表可以拆分串入行

SELECT `Category`, SUBSTRING_INDEX(SUBSTRING_INDEX(t.`Values`, ',', n.n), ',', -1) `value` 
FROM table1 t CROSS JOIN 
(
    SELECT a.N + b.N * 10 + 1 n 
    FROM 
    (SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) a 
    ,(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) b 
    ORDER BY n 
) n 
WHERE n.n <= 1 + (LENGTH(t.`Values`) - LENGTH(REPLACE(t.`Values`, ',', '')))

然后，只需GROUP BY和COUNT

DEMO

SELECT `Category`, `value`, COUNT(*) as cnt 
FROM (
    <previous query> 
    ) T 
GROUP BY `Category`, `value`

来源

2016-11-15 16:19:12

只要你知道鞋帮的位置可能值范围，在这种情况下9.非常好的解决方案胡安卡洛斯。 –

MYSQL从逗号分隔的不同值计数

回答

相关问题