如何优化这个复杂的EAV MYSQL查询？ [英] How to optimize this complicated EAV MYSQL query?

问题描述

是否可以优化我所写的查询

Is it possible to optimize this query I have written

我已经创建了一种动态虚拟数据库，使我的用户能够添加自定义字段而不会影响数据库结构。到目前为止，这是一个非常简化的结构视图。

I've created a sort of dynamic virtual database to give my users the ability to add custom fields without affecting the database structure. Here is a very simplified view of the stucture so far.

tables         | columns

---

---

db_cases       | caseid
db_structure   | fieldname
db_data        | fieldname, data, caseid
db_names       | nameid

• 我们可以通过向db_structure添加一行来创建一个新字段


• 我们希望记录的任何数据记录到db_data。


• 名称存储在db_names中，name_id存储在db_data



我正在尝试将案例输出到html表

I am trying to output the cases to a html table

希望其余的是自我解释，你可以看到它是多么无效。我可以通过连接做同样的事情吗？

Hopefully the rest is self explanatory, you can see how unefficient it is. Can I do the same thing via joins?

SELECT 
case_id,
(SELECT data_field_value 
 FROM db_data 
 WHERE data_case_id = case_id AND data_field_name = 'casestatus'
) AS casestatus,
(SELECT forename_company 
 FROM db_names 
 WHERE name_id = (SELECT data_field_value 
                  FROM db_data 
                  WHERE data_case_id = case_id AND data_field_name = 'client1'
                 )
) AS client1_forename_company
FROM db_cases 

谢谢

推荐答案

实际上，Chibuzo是对的。开始删除它:-)）但之前，玩一点，这是一个很好的脑力，像棋或东西： - ）

Actually, Chibuzo is right. Start by deleting it :-)) But before, play with it a little, it's a good brain excercise, like chess or something :-)

select 
    case_id,
    d_status.data_field_value as case_status,
    d_client1_name.forename_company as client1_forename_company
from db_cases 
        join db_data as d_status 
            on d_status.data_case_id = case_id 
               AND d_status.data_field_name = 'casestatus'
        join db_data as d_client1
            on d_client1.data_case_id = case_id 
               AND d_client1.data_field_name = 'client1'
        join db_names as d_client1_name
            on d_client1_name.name_id = d_client1.data_field_value

我希望这些直接加入没有子查询的效率要高得多，虽然你必须测试它 - 经常会有惊喜的优化。

I would expect these direct joins without subqueries to be much more efficient, though you'll have to test it - there are often surprises in optimizations.

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