MySQL中没有子查询的多重表聚集

Question

I have a "Main" table and multiple associated tables (let's call then T1, T2, etc...). All associated tables are related to MAin in N-1. Now I have a statistic query that collect aggregate informations on the associated tables. Here is the query example:

SELECT *
    Main.*,
    Sub1.*,
    Sub2.*,
    ...
FROM Main
LEFT JOIN (
    SELECT T1.main_id, SUM(T1.col1) as stat1, AVG(T2.col2) as stat2
    FROM T1
    GROUP T1.main_id
) Sub1 ON Sub1.main_id = Main.id
LEFT JOIN (
    SELECT T2.main_id, COUNT|AVG|SUM
    FROM T2
    GROUP T2.main_id
) Sub2 ON Sub2.main_id = Main.id
LEFT JOIN ( T3 ... )

As you can see, I have been using separate GROUP BY subqueries and I join everything together with a set of LEFT JOIN. Everything is working fine until now, but...

I need to create a VIEW based on that query, and as you maybe know, it's not possible to use subqueries in MySQL VIEWs. So the question is: How to rewrite such query without using subqueries?

Note: I know that I can use several sub VIEWs for each subquery. But this is an option I prefer to avoid.

Answer 1

Create seperated view for each subquery then you can call directly view. it will work. or Use mysql workbench to connect mysql DB. and run create view script from mysqlworkbench. It will work.

Example:

create or replace view SUB1 as SELECT T1.main_id, SUM(T1.col1) as stat1, AVG(T2.col2) as stat2
    FROM T1
    GROUP T1.main_id;



create or replace view SUB2 as SELECT T2.main_id, COUNT|AVG|SUM
    FROM T2
    GROUP T2.main_id;

SELECT *
    Main.*,
    Sub1.*,
    Sub2.*,
    ...
FROM Main
LEFT JOIN Sub1 ON Sub1.main_id = Main.id
LEFT JOIN SUB2 on Sub2.main_id = Main.id

.... ....