问题描述
我有一个非规范化表，其中一列包含逗号分隔的列表，该列表是另一个表的外键:
I have an unnormalized table with a column containing a comma separated list that is a foreign key to another table:
+----------+-------------+ +--------------+-------+
| part_id | material | | material_id | name |
+----------+-------------+ +--------------+-------+
| 339 | 1.2mm;1.6mm | | 1 | 1.2mm |
| 970 | 1.6mm | | 2 | 1.6mm |
+----------+-------------+ +--------------+-------+
我想将这些数据读入一个不提供程序语言的搜索引擎.
I want to read this data into a search engine that offers no procedural language.
那么有没有办法要么在该列上建立连接或对该数据运行查询以将适当的条目插入到新表中?结果数据应如下所示:
So is there a way to either make a join on this column or run a query on this data that inserts appropriate entries into a new table? The resulting data should look like this:
+---------+-------------+
| part_id | material_id |
+---------+-------------+
| 339 | 1 |
| 339 | 2 |
| 970 | 2 |
+---------+-------------+
如果 DBMS 支持返回表的函数，但 MySQL 显然不支持，我可以想到一个解决方案.
I could think of a solution if the DBMS supported functions returning a table but MySQL apparently doesn't.
推荐答案
在 MySQL 中可以这样实现
In MySQL this can be achieved as below
SELECT id, length FROM vehicles WHERE id IN ( 117, 148, 126)
+---------------+
| id | length |
+---------------+
| 117 | 25 |
| 126 | 8 |
| 148 | 10 |
+---------------+
SELECT id,vehicle_ids FROM load_plan_configs WHERE load_plan_configs.id =42
+---------------------+
| id | vehicle_ids |
+---------------------+
| 42 | 117, 148, 126 |
+---------------------+
现在要获取逗号分隔的车辆 ID 的长度，请使用以下查询
Now to get the length of comma separated vehicle_ids use below query
Output
SELECT length
FROM vehicles, load_plan_configs
WHERE load_plan_configs.id = 42 AND FIND_IN_SET(
vehicles.id, load_plan_configs.vehicle_ids
)
+---------+
| length |
+---------+
| 25 |
| 8 |
| 10 |
+---------+
更多信息请访问 http://amitbrothers.blogspot.in/2014/03/mysql-split-comma-separated-list-into.html
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