mySQL 唯一值

Question

我需要从表中获取唯一值。我有一列用逗号分隔的关键字。我需要导出一个没有重复的所有关键字的列表。计算每个关键字出现的频率。

根据我的研究，这是一个类似 UNPIVOTING 的函数，列数未知？

例如：

关键词

---

• 红、蓝、黄
• 蓝色、橙色、黑色、白色
• 棕色、黑色、透明、粉红色
• 蓝色、紫色、橙色

结果

颜色 |数

---

• 红1
• 蓝色3
• 黄色1
• 橙色 2
• 黑色2
• 白1
• 棕色 1
• 清除 1
• 粉色1
• 紫1

提前谢谢你！！

** 到目前为止，我已经尝试添加一个explode_table 类型的过程，但意识到我不能从视图中动态调用它。然后我一直在尝试在列上执行反向 GROUP_CONCAT()。我无法生成执行的代码。

---

我的 echo_Me 的回答：

    SELECT  SUBSTRING_INDEX(SUBSTRING_INDEX(sKeywords, ',', n.n), ',', -1) value , count(*) as counts
FROM tblPatternMetadata 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(sKeywords) - LENGTH(REPLACE(sKeywords, ',', ''))) group by value

Answer 1

试试看：

    SELECT  SUBSTRING_INDEX(SUBSTRING_INDEX(t.keywords, ',', n.n), ',', -1) value , count(*) as counts
    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.keywords) - LENGTH(REPLACE(t.keywords, ',', '')))
 group by value

DEMO HERE