Question

我有不同的表格，而且我还要提取数据。

order table

orderId, clientId, buyerId, loadingCompanyId, productTypeId, orderStatusId

user table

userId, userCompanyName

orderStatus table

orderStatusId, orderStatusName,

productType table

productTypeId, productTypeName

所以这些表格。在order table clientId中，buyerId和loadingCompanyId来自用户的表userId，我想获取它的userCompanyName，orderStatusId来自orderStatus表，我想获取orderStatusName，最后一个是productTypeName，productTypeId来自productType表，想要获取productTypeName，但问题在于clientId，buyerId和loadingCompanyId这三个id是userId来自用户表，所以我如何获取客户端，买家和加载公司名称。

Answer 1

这是一些带别名的简单连接

select * 
from order 
join user client on clientId = client.userId
join user buyer on buyerId = buyer.userId
join user company on loadingCompanyId = company.userId
join orderStatus  on orderStatus.orderStatusId= order.orderStatusId
join productType on productType.productTypeId = order.productTypeId

Answer 2

SELECT O.orderId, UserClient.userCompanyName As clientName, UserBuyer.userCompanyName AS buyerName, UserloadingCompany.userCompanyName AS buyerName, OS.orderStatusName, PT.productTypeName
FROM Order O
INNER JOIN user AS UserClient
ON O.clientId = UserClient.userId
INNER JOIN user AS UserBuyer
ON O.buyerId = UserBuyer.userId
INNER JOIN user AS UserloadingCompany
ON O.loadingCompanyId = UserloadingCompany.userId
INNER JOIN orderStatus AS OS
ON O.orderStatusId = OS.orderStatusId
INNER JOIN productType AS PT
ON O.productTypeId = PT.productTypeId

相同和不同表中的不同ID的多个连接

2 个答案: