Unions

Queries of compatible types can be combined to unions with the union and unionAll methods:

  object Managers extends Table[(Int, String, String)]("managers") {
    def id = column[Int]("id")
    def name = column[String]("name")
    def department = column[String]("department")
    def * = id ~ name ~ department
  }

  object Employees extends Table[(Int, String, Int)]("employees") {
    def id = column[Int]("id")
    def name = column[String]("name")
    def manager = column[Int]("manager", O.NotNull)
    def * = id ~ name ~ manager
  }

  ...

      val q1 = for(m <- Managers if m.department === "IT") yield m.id ~ m.name

      val q2 = for(e <- Employees) yield e.id ~ e.name

      val q3 = for(id ~ name <- q1 union q2) yield id ~ name

unionAll simply combines the rows produced by both queries, whereas union filters out duplicate rows.