Question

我有以下3张桌子：

CREATE TABLE Pins (
    email varchar(100) NOT NULL,
    boardID int NOT NULL,
    ));

CREATE TABLE Boarders (
    email varchar(100) NOT NULL,
    boardID int NOT NULL,
    FOREIGN KEY (categoryName) REFERENCES Category (name));


CREATE TABLE User (
    email varchar(100) NOT NULL,
    name varchar(50),
    PRIMARY KEY (email));

我要这样查询查询结果：对于每个Pin，请显示说明

这显然行不通，但是关于如何显示以上内容的任何建议？

Answer 1

select p.description ,c.title, u.name from PushPin p,CorkBoard c, User u
    where c.email=u.email and c.email =p.email  and c.boardID = p.boardID 
      order by p.description

Answer 2

是的，这将要求您加入三个表。

类似以下代码的东西应该可以工作。仅定义外键关系并不意味着您不需要在查询时加入。

SELECT PP.description, CB.title, U.name
FROM PushPin PP JOIN CorkBoard CB ON PP.boardID = CB.boardID
   JOIN USSER U ON PP.email = U.email
WHERE description like '$search'
ORDER BY description;

尝试从3个不同的表中查找3列

2 个答案: