为什么这两个Slick查询不相等?

由于 trying to make a Slick query more readable ,我有一个查询构造函数,它可以工作

val q = Users.filter(_.id === userId) join People on {
  case (u, p) => u.personId === p.id
} joinLeft Addresses on {
  case ((u, p), a) => p.addressId === a.id
} joinLeft Businesses on {
  case (((u, p), a), b) => p.businessId === b.id
} joinLeft Addresses on {
  case ((((u, p), a), b), ba) => b.flatMap(_.addressId) === ba.id
} map {
  case ((((u, p), a), b), ba) => (p, a, b, ba)
}

这一个我认为是等效的,但不起作用:

val q = Users.filter(_.id === userId) join People joinLeft Addresses joinLeft Businesses joinLeft Addresses on {
  case ((((u, p), a), b), ba) =>
    u.personId === p.id &&
    p.addressId === a.flatMap(_.id) &&
    p.businessId === b.flatMap(_.id) &&
    b.flatMap(_.addressId) === ba.id
} map {
  case ((((u, p), a), b), ba) => (p, a, b, ba)
} 

第二个似乎返回了一个包含多个目标配置文件的配置文件列表。

为什么它们不一样?

“等效”SQL(即此构造的目标)是:

select p.*, a1.*, b.*, a2.* from Users u 
innerJoin People p on (u.personId == p.id) 
leftJoin Addresses a1 on (p.addressId == a1.id) 
leftJoin Businesses b on (p.businessId == b.id) 
leftJoin Addresses a2 on ( b.addressId == a2.id)