通过Lamda表达式使用Select和Where子句连接多个表

Question

我有如下3张桌子

表1：Brand

+-------+---------+-------+
|Code(k)| Name    | Sale  | *Code - set Primary Key
+-------+---------+-------+  
| AP    | Apple   | False |  
+-------+---------+-------+  
| SS    | SamSung | False |  
+-------+---------+-------+  
| N     | Nokia   | False |  
+-------+---------+-------+

表2：Category
（（表1：Code和表2：表{2：Brand中的Brand）

Category

表3：+-------+-------------+-------+---------+ | ID(k) | Category | Brand | Manager | *ID - set Primary Key +-------+-------------+-------+---------+ | 1 | BasicPhone | SS | M1 | +-------+-------------+-------+---------+ | 2 | SmartPhone | AP | M1 | +-------+-------------+-------+---------+ | 3 | CameraPhone | SS | M1 | +-------+-------------+-------+---------+ | 4 | Tablet | SS | M1 | +-------+-------------+-------+---------+ | 5 | Iphone | AP | M1 | +-------+-------------+-------+---------+ | 6 | Ipad | AP | M1 | +-------+-------------+-------+---------+

Product

我如何通过+-------------+-------------+-------------+ | Category | CategoryDes | Description | * no Primary Key +-------------+-------------+-------------+ | BasicPhone | NoCamera | Contact | +-------------+-------------+-------------+ | SmartPhone | Camera | TakePhoto | +-------------+-------------+-------------+ | CameraPhone | GoodCamera | Selfie | +-------------+-------------+-------------+ | Tablet | BigScreen | ReadNews | +-------------+-------------+-------------+ | Iphone | Iphone7 | Something.. | +-------------+-------------+-------------+ | Ipad | Ipad2 | Ipad... | +-------------+-------------+-------------+ 将表1：Brand和表3：Product加入表2：Category

我想要这样的结果

Lambda expression

更新：

我试图将表1加入表2

+-----+------------+-------+---------+---------+-------+-------------+-------------+
| ID  | Category   | Brand | Manager | Name    | Sale  | CategoryDes | Description |
+-----+------------+-------+---------+---------+-------+-------------+-------------+
| 1   | BasicPhone | SS    | M1      | SamSung | False | NoCamera    | Contact     |
+-----+------------+-------+---------+---------+-------+-------------+-------------+
| 2   | SmartPhone | AP    | M1      | Apple   | False | Camera      | TakePhoto   |
+-----+------------+-------+---------+---------+-------+-------------+-------------+
|                                ...........                                       |
+-----+------------+-------+---------+---------+-------+-------------+-------------+
| ... | null       | null  | N       | Nokia   | False | null        | null        | *null (allowed)
+-----+------------+-------+---------+---------+-------+-------------+-------------+

Answer 1

@Holger的评论是正确的，您处在正确的轨道上，只需要另一个联接即可。像这样：

func useWalkAndPrintTreeValues(k int) {
    c := make(chan int, 10)

    go Walk(tree.New(k), c, true)

    for x := range c {
        fmt.Print(x, " ")   
    }
}

免责声明，我没有对此进行测试。