mysql - mysql连接三个表

Question

我有三个表，其中包含供应商详细信息、服务和地点。所有这些都有一个公共(public)字段作为供应商 ID。

我想展示与供应商相关的服务和场所。

我尝试了一些连接，但没有得到结果。

我尝试过的其中一个是:

SELECT services.serviceId as Id, 
services.service_name as service_name,
services.entry_by as entry_by,
services.servicetypeId as servicetypeId, 
services.latitude as latitude,
services.longitude as longitude, 
services.active as active, 

vendorDetails.username, 
vendorDetails.emailId, 
vendorDetails.vendorAddress,
vendorDetails.vendorName,
vendorDetails.mobileno, 

venues.venueId as Id, 
venues.venue_name as venue_name, 
venues.entry_by as entry_by, 
venues.venuetypeId as venuetypeId, 
venues.latitude as latitude,
venues.longitude as longitude,
venues.active as active 

FROM `vendorDetails` v

inner join `venues` venue on v.vendorId = venues.venueId
inner join `services` s on v.vendorId  = s.vendorId

但它显示 services.serviceId 的错误为未知列。我检查了服务表中是否存在该列。

我怎样才能得到这个？谢谢..

Answer 1

实际上，您使用表别名作为表v s venue vendorDetails services field 分别。因此，相应的表名被替换为该特定查询的别名。因此原始表名变得未知。在 inner joinvenuesvenue on v.vendorId =venues.venueId 中，您将 vendorId 与 venueId 进行比较，这将返回空结果集。请尝试以下查询

SELECT 
    s.serviceId as Id, 
    s.service_name as service_name,
    s.entry_by as entry_by,
    s.servicetypeId as servicetypeId, 
    s.latitude as latitude,
    s.longitude as longitude, 
    s.active as active, 

    v.username, 
    v.emailId, 
    v.vendorAddress,
    v.vendorName,
    v.mobileno, 

    venue.venueId as Id, 
    venue.venue_name as venue_name, 
    venue.entry_by as entry_by, 
    venue.venuetypeId as venuetypeId, 
    venue.latitude as latitude,
    venue.longitude as longitude,
    venue.active as active 

FROM 
    `vendorDetails` v

Inner Join
    `venues` venue on v.vendorId = venue.vendorId 
Inner Join 
    `services` s on v.vendorId  = s.vendorId