Question

我将值存储在MySql表中，如下所示：

id        content_id   group_id   value
================================================
12274     251          5          4 GB, 512 MB RAM
12323     252          5          32 GB, 2 GB RAM
12372     253          5          8 GB, 2 GB RAM
12421     254          5          8 GB, 1 GB RAM
12470     255          5          8 GB, 1 GB RAM
12519     256          5          4 GB, 512 MB RAM

其中“值”列中包含内部存储器和移动式RAM的行，每行中都用逗号分隔，现在我要在“值”列中执行搜索结果，这将使我获得RAM“ 512 MB”和“ 2 GB”之间的所有行

我如何在MySql中执行此操作？请帮助

Answer 1

开始时是作为注释，但超出了可用空间。我们可以给您一个查询，但是它会很肿并且很丑。将表设计固定为这样会更好：

id        content_id   group_id   value_low   value_high
=========================================================
12274     251          5          0.512       4
12323     252          5          2           32
12372     253          5          2           8
12421     254          5          1           8
12470     255          5          1           8
12519     256          5          0.512       4

首先要了解的重点是，我们为存储范围的低端和高端分别设置了真实的列。第二，我们到处都使用一个统一的单位GB。考虑到这些更改，我们可以轻松编写您的查询：

SELECT *
FROM yourTable
WHERE value_high >= 2.0 AND value_low <= 0.512;

Answer 2

以逗号分隔的值很难查询。
需要使用棘手的SQL将项目解析为记录，因此理想情况下，您应该像Tim Biegeleisen建议的那样进行规范化。

另外，当您拥有使用正则表达式的MySQL 8.0时，更容易实现。

查询

SELECT 
  #remove duplicates
  DISTINCT 
      t.*
    , TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)) AS tag
    , CASE
        WHEN LOCATE('GB', UPPER(TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)))) > 0
        # return GB to MB calculated                                               
        THEN (TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)) + 0.00) * 1024
        # return MB value                                  
        ELSE TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)) + 0.00                        
      END AS MB_calculated                                                
FROM (

  SELECT
    @number := @number + 1 AS number
  FROM (
    (SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) row1
     CROSS JOIN
    (SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) row2
     CROSS JOIN 
    (SELECT @number:=0) AS init_user_params
  )  
) 
 AS numbers
CROSS JOIN t
WHERE 
  CASE
        WHEN LOCATE('GB', UPPER(TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)))) > 0
        # return GB to MB calculated                                               
        THEN (TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)) + 0.00) * 1024
        # return MB value                                  
        ELSE TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(t.value, ',', numbers.number), ',', -1)) + 0.00                        
      END BETWEEN 512 AND (2 * 1024)

结果

| id    | content_id | group_id | value            | tag        | MB_calculated |
| ----- | ---------- | -------- | ---------------- | ---------- | ------------- |
| 12274 | 251        | 5        | 4 GB, 512 MB RAM | 512 MB RAM | 512           |
| 12323 | 252        | 5        | 32 GB, 2 GB RAM  | 2 GB RAM   | 2048          |
| 12372 | 253        | 5        | 8 GB, 2 GB RAM   | 2 GB RAM   | 2048          |
| 12421 | 254        | 5        | 8 GB, 1 GB RAM   | 1 GB RAM   | 1024          |
| 12470 | 255        | 5        | 8 GB, 1 GB RAM   | 1 GB RAM   | 1024          |
| 12519 | 256        | 5        | 4 GB, 512 MB RAM | 512 MB RAM | 512           |

请参阅demo

如何从数据库表中获取RAM在1 MB到2 GB之间的所有设备？

2 个答案: