[英]Mysql query of multiple tables joined
我有以下表格:
machine_machine
id | machineid
1 | EE100034442
item_item
id | upc | name
2 | 10001 | Snickers
machine_setup
id | machine_id | selection | item_id
3 | 1 | A1 | 1
我試圖通過加入表來獲得以下輸出。
machine_setup.machine_id = machine_machine.machineid,machine_setup.selection,item_item.upc,item_item.name
EE100034442 A1 10001 Snickers
主引用表將使用表machine_setup,因為它對每個machine_id具有多個選擇。
我不太確定我理解這個問題,但是您想要的sql就像;
Select machine1.machineid, setup.Selection, item.upc, item.name
From Machine_machine machine1 --Set alias for the table
Inner Join machine_setup setup on setup.machine_id = machine1.id --This looks like a link table to me
Inner Join item_item item on setup.item_id = item.id -- in your example this wouldn't link as item_id is 1 in the machine_setup
在您的示例中,machine_setup item_id設置為1,這意味着它不會鏈接到item_item表。 我假設這是一個錯誤。 如果您需要更多信息,請與我們聯系。
根據目前可以加入的唯一ID,請考慮以下事項:
create table machine_machine
( id int auto_increment primary key,
machineid varchar(50) not null
);
create table item_item
( id int auto_increment primary key,
upc varchar(30) not null,
name varchar(100) not null
);
create table machine_setup
( id int auto_increment primary key,
machine_id int not null,
selection varchar(30) not null
);
insert machine_machine(machineid) values ('EE100034442');
insert item_item(upc,name) values ('10001','Snickers');
insert machine_setup(machine_id,selection) values (1,'A1'),(1,'A2'),(1,'A(n)');
select mm.machineid,ms.selection,ii.upc,ii.name
from machine_setup ms
join machine_machine mm
on mm.id=ms.machine_id
join item_item ii
on ii.id=ms.machine_id;
+-------------+-----------+-------+----------+
| machineid | selection | upc | name |
+-------------+-----------+-------+----------+
| EE100034442 | A1 | 10001 | Snickers |
| EE100034442 | A2 | 10001 | Snickers |
| EE100034442 | A(n) | 10001 | Snickers |
+-------------+-----------+-------+----------+
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