mysql显示公司的所有其他结果

Question

I have a question. This is my database structure

**company**
id | name
---------
1, Test
2, demo

**address**
id | name
---------
1, test1
2, test2
3, bla6

**address_company**
id | address_id | company_id
1, 1, 1
2, 2, 1
3, 3, 2

My query is this:

SELECT company.name, address.name FROM company 
INNER JOIN address_company on address_company.company_id = company.id
INNER JOIN address on address.id = address_company.address_id

This works. But I need to filter results.

So when people click address (frontend): test1, it only needs to show company: Test

I can do this:

WHERE address.name = "test1"

This also works but I need to filter further so what I need is

WHERE address.name = "test1" AND address.name = "test2" 

But this doesn't work, it doesn't show results. I can only filter on 1 address and I need to filter on more addresses.

Hope you guys can understand me and can help me. THANKS!

Answer 1

Use OR instead of and, or use the in() structure:

WHERE address.name = 'test1' OR address.name = 'test2'


WHERE address.name IN('test1', 'test2' )

Note: I hope that the below join condition was just typed incorrectly in the question:

 INNER JOIN address on address.id = address_company.id

Answer 2

The below strategy leans on the unique key(address_id,company_id) making sure there are no duplicates at that combo-level

Schema

create table company
(   id int auto_increment primary key,
    name varchar(100) not null
);
insert company(name) values ('Test'),('demo');

create table address
(   id int auto_increment primary key,
    name varchar(100) not null
);
insert address(name) values ('test1'),('test2'),('bla6');

create table address_company
(   id int auto_increment primary key,
    address_id int not null,
    company_id int not null,
    unique key(address_id,company_id) -- no dupes allowed ! I am banking on this below
);
insert address_company(address_id,company_id) values (1,1),(2,1),(3,2);

The queries

select company_id,count(*) theCount from address_company 
where address_id in (1,2) 
group by company_id having theCount>1;

+------------+----------+
| company_id | theCount |
+------------+----------+
|          1 |        2 |
+------------+----------+

select company_id,count(*) theCount from address_company 
where address_id in (select id from address where name in ('test1','test2'))
group by company_id having theCount>1;

+------------+----------+
| company_id | theCount |
+------------+----------+
|          1 |        2 |
+------------+----------+

So if the group by / having returns greater than 1 for the count, where I literally went after name1 and name2, then I know that row qualifies. And that row of course then has name1 and name2.

Back to the unique key part: This assures we aren't tricked in having a company with the same address twice. Which first off doesn't make sense, and also that would mess up this strategy.

Obviously the schema needs some index help, and FK's wouldn't break anyone's heart. But this is just a strawman.