MySQL 如何在sql中创建INNER JOIN多个表
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How to create INNER JOIN multiple tables in sql
提问by user_unknown
I have 3 tables: Products, Vendors and Prices. Prices has product_id and vendor_id as foreign keys. Now i want to show Prices as:
我有 3 个表：产品、供应商和价格。Prices 有 product_id 和 vendor_id 作为外键。现在我想将价格显示为：
price_id:product_name:vendor_name:price
price_id:product_name:vendor_name:price
Something like:
就像是：
SELECT p.product, v.vendor, pc.price
FROM Products AS p,
Vendors AS v
INNER JOIN Prices AS pc
ON p.product_id = pc.product_id
INNER JOIN Prices AS pc
ON v.vendor = pc.vendor_id
but I didnt get it work.
但我没有得到它的工作。
回答by Marek Kwiendacz
Try this:
尝试这个：
SELECT pr.price_id, p.product_name v.vendor_name, pr.price
FROM Prices AS pr
LEFT JOIN Products AS p ON p.product_id = pr.product_id
LEFT JOIN Vendors AS v ON v.vendor = pr.vendor_id
回答by Matt Asbury
You can't use the same alias twice
您不能两次使用相同的别名
Prices as pc
You can only use pc once.
您只能使用一次电脑。
回答by Ruben
or write 3 diffent select statements and join them with UNION
或编写 3 条不同的 select 语句并使用 UNION 加入它们
回答by hugo hidalgo
Hello I have 3 different tables, and this query works well.
您好，我有 3 个不同的表，此查询运行良好。
SELECT A.ID_USER,A.NAME,D.ADDRESS,B.ID_STATE,B.STATE,A.ID_COUNTRY,C.COUNTRY
FROM market.USER A
INNER JOIN market.state B
ON A.ID_STATE=B.ID_STATE
INNER JOIN market.country C
ON A.ID_COUNTRY=C.ID_COUNTRY
INNER JOIN market.contact D
ON A.ID_CONTACT=D.ID_CONTACT
try to do that for your own requirement.
尝试根据您自己的要求执行此操作。
