SQL外键-在单个ID中有多个产品？

Question

有人可以向我解释如何做吗？

Table "SC": id_sc - id_name - id_prod - qtd
Table "Name": id_name - name seller
Table "Prod": id_prod - name prod

示例：

Table Name: id 1 - name Ivan
Table Prod: id 1 - name Orange
            id 2 - name Apple
            id 3 - name Banana             

Table SC: 2 - Ivan - Orange, Apple, Banana

我需要SC表在一个ID中包含多个产品。 我不能做表之间的关系。

Answer 1

您可能没有这样的引用/映射表（这就是SC的外观）。

例如，考虑以下内容：-

DROP TABLE IF EXISTS name;
DROP TABLE IF EXISTS prod;
DROP TABLE IF EXISTS sc;
CREATE TABLE IF NOT EXISTS name (id_name INTEGER PRIMARY KEY, name TEXT);
CREATE TABLE IF NOT EXISTS prod (id_prod INTEGER PRIMARY KEY, name TEXT);
CREATE TABLE IF NOT EXISTS sc (id_sc INTEGER PRIMARY KEY, id_name INTEGER, id_prod INTEGER, qtd INTEGER, UNIQUE(id_name,id_prod));
INSERT INTO name (name) VALUES ('Ivan'),('Fred'),('Mary');
INSERT INTO prod (name) VALUES ('Apple'),('Banana'),('Oranage');
INSERT INTO sc (id_name,id_prod,qtd) VALUES
    (1,1,10), -- Ivan has 10 apples
    (2,1,9), -- Fred has 9 Apples
    (3,1,21), -- Mary has 21 Apples
    (1,2,33), -- Ivan has 33 Bananas
    (3,2,16), -- Mary has 16 Bananas
    (2,3,22), -- Fred has 22 Oranges
    (3,3,5) -- Mary has 5 Oranges
;
SELECT name.name ||' has '||qtd||' '||prod.name AS who_has_what FROM sc 
    JOIN name ON sc.id_name = name.id_name
    JOIN prod ON sc.id_prod = prod.id_prod
;
SELECT name.name, group_concat(prod.name) FROM sc
  JOIN name ON sc.id_name = name.id_name
  JOIN prod ON sc.id_prod = prod.id_prod 
GROUP BY name.id_name
;

因此表SC将名称映射到产品。

查询的结果是：-