内部连接3表

我在我的数据库中有6个表 booking_system 。现在我想要加入car_space，transaction和sport_facilities。但是，我遇到了问题。内部连接3表

当我分别使用这两个sql命令时，这些命令也可以运行，我可以得到我想要的结果。

-- car_space INNER JOIN transaction 
SELECT * FROM car_space INNER JOIN transaction ON car_space.carSpaceId = transaction.carSpaceId ORDER BY transactionId; 
-- sport_facilities INNER JOIN transaction 
SELECT * FROM sport_facilities INNER JOIN transaction ON sport_facilities.sportFacilitiesId = transaction.sportFacilitiesId ORDER BY transactionId;

然后，我将它们合并为一个命令。

-- Combine But Not Work 
SELECT * FROM transaction 
INNER JOIN car_space ON transaction.carSpaceId = car_space.carSpaceId 
INNER JOIN sport_facilities ON transaction.sportFacilitiesId = sport_facilities.sportFacilitiesId 
ORDER BY transactionId;

虽然这可以运行，但没有结果或记录显示。

我想要做的是当我键入一个transactionId时，数据库可以被找到记录在哪个表（car_space/sport_facilities）中。例如：我输入WHERE transactionId = 1 数据库可以搜索这是从sport_facilities表，而不是car_space。

谢谢。这里有一些代码供参考。

-- Create a database 
CREATE DATABASE booking_system; 

-- Use This database 
USE booking_system; 

-- Create smartcart table 
CREATE TABLE card(
    cardId CHAR(8)  NOT NULL, 
    PRIMARY KEY (cardId) 
); 

-- Insert some recond to card table 
INSERT INTO card VALUES 
    ('4332A0D5'), 
    ('637ED500'), 
    ('B3895A02'), 
    ('E32F3702') 
; 

-- Create user table 
CREATE TABLE user(
    userId  INT(5)   NOT NULL AUTO_INCREMENT, 
    cardNo  CHAR(8)   NOT NULL, 
    firstName VARCHAR(255) NOT NULL, 
    lastName VARCHAR(255) NOT NULL, 
    sex   CHAR(1)   NOT NULL, 
    dob   DATE   NOT NULL, 
    hkid  CHAR(8)   NOT NULL, 
    email  VARCHAR(255) NOT NULL, 
    telNo  INT(8)   NOT NULL, 
    PRIMARY KEY (userId), 
    FOREIGN KEY (cardNo) REFERENCES card (cardId) ON DELETE CASCADE, 
    UNIQUE (hkid) 
); 

-- Alter user table 
ALTER TABLE user AUTO_INCREMENT = 16001; 

-- Insert some recond to user table 
INSERT INTO user VALUES 
    ('','4332A0D5','Andy','Ding','M','1962-04-20','K5216117','[email protected]','98626229'), 
    ('','637ED500','Emma','Dai','F','1972-06-15','D5060339','[email protected]','62937453'), 
    ('','B3895A02','Brinsley','Au','F','1984-02-24','P8172327','[email protected]','91961624'), 
    ('','E32F3702','Eric','Fong','M','1990-04-15','Y1129323','[email protected]','98428731') 
; 

-- Create car space price table 
CREATE TABLE car_space_price(
    spaceNo    INT(2)  NOT NULL AUTO_INCREMENT, 
    price    INT(2)  NOT NULL, 
    carSpaceDescription VARCHAR(16), 
    CHECK (carSpaceDescription IN ('motorcycles','small vehicles','medium vehicles','large vehicles')), 
    PRIMARY KEY (spaceNo) 
); 

-- Insert some recond to car space price table 
INSERT INTO car_space_price VALUES 
    ('','10','motorcycles'),  -- 1 
    ('','10','motorcycles'),  -- 2 
    ('','10','motorcycles'),  -- 3 
    ('','10','motorcycles'),  -- 4 
    ('','10','motorcycles'),  -- 5 
    ('','20','small vehicles'),  -- 6 
    ('','20','small vehicles'),  -- 7 
    ('','20','small vehicles'),  -- 8 
    ('','20','small vehicles'),  -- 9 
    ('','20','small vehicles'),  -- 10 
    ('','40','medium vehicles'), -- 11 
    ('','40','medium vehicles'), -- 12 
    ('','40','medium vehicles'), -- 13 
    ('','80','large vehicles'),  -- 14 
    ('','80','large vehicles')  -- 15 
; 

-- Create car space table 
CREATE TABLE car_space(
    carSpaceId INT(5)  NOT NULL AUTO_INCREMENT, 
    spaceNo  INT(2)  NOT NULL, 
    cardNo  VARCHAR(8) NOT NULL, 
    inTime  DATETIME, 
    outTime  DATETIME, 
    PRIMARY KEY (carSpaceId), 
    FOREIGN KEY (spaceNo) REFERENCES car_space_price (spaceNo) ON DELETE CASCADE, 
    FOREIGN KEY (cardNo) REFERENCES card (cardId) ON DELETE CASCADE 
); 

-- Insert some recond to car space table 
INSERT INTO car_space VALUES 
    ('','2','E32F3702','2015-02-23 14:24:18','2015-02-23 17:01:43'), -- 1 --16004 
    ('','6','B3895A02','2016-02-24 11:56:43','2016-02-25 09:21:08'), -- 2 --16003 
    ('','2','E32F3702','2016-02-24 16:42:34','2016-02-24 21:02:45'), -- 3 --16004 
    ('','2','E32F3702','2016-02-25 14:25:32','2016-02-25 17:03:54'), -- 4 --16004 
    ('','6','B3895A02','2016-02-25 17:12:11','2016-02-25 20:58:18'), -- 5 --16003 
    ('','13','637ED500','2016-02-25 19:17:03','2016-02-27 18:05:28'), -- 6 --16002 
    ('','6','B3895A02','2016-02-25 21:14:03','2016-02-25 23:53:28'), -- 7 --16003 
    ('','6','B3895A02','2016-02-26 08:46:23','2016-02-26 17:21:08'), -- 8 --16003 
    ('','2','E32F3702','2016-02-26 14:15:45','2016-02-26 21:01:15'), -- 9 --16004 
    ('','6','B3895A02','2016-02-27 09:42:13','2016-02-27 15:48:45'), -- 10 --16003 
    ('','2','E32F3702','2016-02-27 13:25:45','2016-02-27 15:15:45'), -- 11 --16004 
    ('','6','B3895A02','2016-02-28 10:57:16','2016-02-28 14:41:25'), -- 12 --16003 
    ('','2','E32F3702','2016-02-28 11:47:32','2016-02-28 13:43:15'), -- 13 --16004 
    ('','13','637ED500','2016-02-28 13:04:43','2016-03-02 22:39:46'), -- 14 --16002 
    ('','2','E32F3702','2016-02-28 14:42:34','2016-02-28 21:47:45'), -- 15 --16004 
    ('','6','B3895A02','2016-02-29 08:50:42','2016-02-29 14:28:42'), -- 16 --16003 
    ('','2','E32F3702','2016-02-29 12:12:35','2016-02-29 16:45:28'), -- 17 --16004 
    ('','6','B3895A02','2016-03-01 11:26:43','2016-03-01 14:56:26'), -- 18 --16003 
    ('','6','B3895A02','2016-03-03 13:45:26','2016-03-03 17:54:18')  -- 19 --16003 
; 

-- Create sport facilities price table 
CREATE TABLE sport_facilities_price(
    sportNo    INT(2)  NOT NULL AUTO_INCREMENT, 
    sportType   VARCHAR(10) NOT NULL, 
    price    INT(2)  NOT NULL, 
    sportDescription VARCHAR(20), 
    PRIMARY KEY (sportNo) 
); 

-- Insert some recond to sport facilities price table 
INSERT INTO sport_facilities_price VALUES 
    ('','snooker','15','Snooker Room 1'),   -- 1 
    ('','snooker','15','Snooker Room 2'),   -- 2 
    ('','snooker','15','Snooker Room 3'),   -- 3 
    ('','snooker','15','Snooker Room 4'),   -- 4 
    ('','table_tennis','15','Table Tennis Room 1'), -- 5 
    ('','table_tennis','15','Table Tennis Room 2'), -- 6 
    ('','table_tennis','15','Table Tennis Room 3'), -- 7 
    ('','table_tennis','15','Table Tennis Room 4'), -- 8 
    ('','tennis','30','Tennis Vanue 1'),   -- 9 
    ('','tennis','30','Tennis Vanue 2'),   -- 10 
    ('','badminton','30','Badminton Vanue 1'),  -- 11 
    ('','badminton','30','Badminton Vanue 2'),  -- 12 
    ('','basketball','60','Hall')     -- 13 
; 

-- Create sport facilities table 
CREATE TABLE sport_facilities(
    sportFacilitiesId INT(5)  NOT NULL AUTO_INCREMENT, 
    sportNo    INT(2)  NOT NULL, 
    cardNo    VARCHAR(8) NOT NULL, 
    bookDate   DATE  NOT NULL, 
    startTime   TIME  NOT NULL, 
    endTime    TIME  NOT NULL, 
    PRIMARY KEY (sportFacilitiesId), 
    FOREIGN KEY (sportNo) REFERENCES sport_facilities_price (sportNo) ON DELETE CASCADE, 
    FOREIGN KEY (cardNo) REFERENCES card (cardId) ON DELETE CASCADE 
); 

-- Insert some recond to sport facilities table 
INSERT INTO sport_facilities VALUES 
    ('','1','E32F3702','2015-02-23','12:00:00','14:00:00'),  -- 1 --16004 
    ('','5','B3895A02','2016-02-23','14:00:00','15:00:00'),  -- 2 --16003 
    ('','8','637ED500','2016-02-23','17:00:00','21:00:00'),  -- 3 --16002 
    ('','2','E32F3702','2016-02-24','09:00:00','11:00:00'),  -- 4 --16004 
    ('','5','4332A0D5','2016-02-24','13:00:00','14:00:00'),  -- 5 --16001 
    ('','7','637ED500','2016-02-24','15:00:00','17:00:00'),  -- 6 --16002 
    ('','8','B3895A02','2016-02-24','16:00:00','18:00:00'),  -- 7 --16003 
    ('','10','4332A0D5','2016-02-25','09:00:00','10:00:00'), -- 8 --16001 
    ('','12','B3895A02','2016-02-25','13:00:00','14:00:00'), -- 9 --16003 
    ('','6','637ED500','2016-02-25','21:00:00','22:00:00'),  -- 10 --16002 
    ('','4','637ED500','2016-02-26','11:00:00','13:00:00'),  -- 11 --16002 
    ('','8','4332A0D5','2016-02-26','22:00:00','23:00:00'),  -- 12 --16001 
    ('','13','B3895A02','2016-02-27','09:00:00','14:00:00'), -- 13 --16003 
    ('','4','637ED500','2016-02-28','12:00:00','14:00:00'),  -- 14 --16002 
    ('','3','B3895A02','2016-02-28','14:00:00','15:00:00'),  -- 15 --16003 
    ('','4','E32F3702','2016-02-28','17:00:00','19:00:00'),  -- 16 --16004 
    ('','5','B3895A02','2016-02-28','21:00:00','22:00:00'),  -- 17 --16003 
    ('','2','4332A0D5','2016-02-28','21:00:00','23:00:00'),  -- 18 --16001 
    ('','10','E32F3702','2016-02-28','19:00:00','20:00:00'), -- 19 --16004 
    ('','11','B3895A02','2016-02-29','11:00:00','13::00:00'), -- 20 --16003 
    ('','8','E32F3702','2016-02-29','12:00:00','14:00:00'),  -- 21 --16004 
    ('','4','4332A0D5','2016-02-29','15:00:00','18:00:00'),  -- 22 --16001 
    ('','6','E32F3702','2016-03-01','09:00:00','11:00:00'),  -- 23 --16004 
    ('','5','637ED500','2016-03-01','12:00:00','15:00:00'),  -- 24 --16002 
    ('','3','B3895A02','2016-03-02','09:00:00','11:00:00'),  -- 25 --16003 
    ('','7','4332A0D5','2016-03-02','12:00:00','13:00:00'),  -- 26 --16001 
    ('','4','637ED500','2016-03-02','15:00:00','17:00:00'),  -- 27 --16002 
    ('','1','E32F3702','2016-03-02','19:00:00','22:00:00'),  -- 28 --16004 
    ('','12','4332A0D5','2016-03-03','11:00:00','13:00:00'), -- 29 --16001 
    ('','9','E32F3702','2016-03-03','15:00:00','16:00:00'),  -- 30 --16004 
    ('','10','B3895A02','2016-03-03','09:00:00','11:00:00'), -- 31 --16003 
    ('','4','637ED500','2016-03-04','11:00:00','12:00:00'),  -- 32 --16002 
    ('','8','E32F3702','2016-03-04','14:00:00','16:00:00'),  -- 33 --16004 
    ('','6','B3895A02','2016-03-05','19:00:00','21:00:00'),  -- 34 --16003 
    ('','13','E32F3702','2016-03-05','11:00:00','12:00:00'), -- 35 --16004 
    ('','8','637ED500','2016-03-05','14:00:00','15:00:00'),  -- 36 --16002 
    ('','4','4332A0D5','2016-03-05','16:00:00','18:00:00'),  -- 37 --16001 
    ('','5','E32F3702','2016-03-06','13:00:00','15:00:00'),  -- 38 --16004 
    ('','9','B3895A02','2016-03-06','17:00:00','18:00:00'),  -- 39 --16003 
    ('','11','4332A0D5','2016-03-07','20:00:00','21::00:00'), -- 40 --16001 
    ('','5','B3895A02','2016-03-07','22:00:00','23:00:00')  -- 41 --16003 
; 

-- Create transaction table 
CREATE TABLE transaction(
    transactionId  INT(5) UNSIGNED ZEROFILL NOT NULL AUTO_INCREMENT, 
    userId    INT(5) NOT NULL, 
    carSpaceId   INT(5), 
    sportFacilitiesId INT(5), 
    transactionDate  DATE NOT NULL, 
    PRIMARY KEY (transactionId), 
    FOREIGN KEY (userId) REFERENCES user (userId) ON DELETE CASCADE, 
    FOREIGN KEy (carSpaceId) REFERENCES car_space (carSpaceId) ON DELETE CASCADE, 
    FOREIGN KEY (sportFacilitiesId) REFERENCES sport_facilities (sportFacilitiesId) ON DELETE CASCADE 
); 

-- Insert some recond to transaction table 
INSERT INTO transaction VALUES 
    ('','16004',NULL,'1','2015-02-23'),  -- 1 -- Sport Facilities 
    ('','16003',NULL,'5','2015-02-23'),  -- 2 -- Sport Facilities 
    ('','16004','2',NULL,'2015-02-23'),  -- 3 -- Car Space 
    ('','16002',NULL,'8','2015-02-23'),  -- 4 -- Sport Facilities 
    ('','16004',NULL,'2','2016-02-24'),  -- 5 -- Sport Facilities 
    ('','16003','6',NULL,'2016-02-24'),  -- 6 -- Car Space 
    ('','16001',NULL,'5','2016-02-24'),  -- 7 -- Sport Facilities 
    ('','16002',NULL,'7','2016-02-24'),  -- 8 -- Sport Facilities 
    ('','16003',NULL,'8','2016-02-24'),  -- 9 -- Sport Facilities 
    ('','16004','2',NULL,'2016-02-24'),  -- 10 -- Car Space 
    ('','16001',NULL,'10','2016-02-25'), -- 11 -- Sport Facilities 
    ('','16003',NULL,'12','2016-02-25'), -- 12 -- Sport Facilities 
    ('','16004','2',NULL,'2016-02-25'),  -- 13 -- Car Space 
    ('','16003','6',NULL,'2016-02-25'),  -- 14 -- Car Space 
    ('','16002','13',NULL,'2016-02-25'), -- 15 -- Car Space 
    ('','16002',NULL,'6','2016-02-25'),  -- 16 -- Sport Facilities 
    ('','16003','6',NULL,'2016-02-25'),  -- 17 -- Car Space 
    ('','16003','6',NULL,'2016-02-26'),  -- 18 -- Car Space 
    ('','16002',NULL,'4','2016-02-26'),  -- 19 -- Sport Facilities 
    ('','16004','2',NULL,'2016-02-26'),  -- 20 -- Car Space 
    ('','16001',NULL,'8','2016-02-26'),  -- 21 -- Sport Facilities 
    ('','16003',NULL,'13','2016-02-27'), -- 22 -- Sport Facilities 
    ('','16003','6',NULL,'2016-02-27'),  -- 23 -- Car Space 
    ('','16004','2',NULL,'2016-02-27'),  -- 24 -- Car Space 
    ('','16003','6',NULL,'2016-02-28'),  -- 25 -- Car Space 
    ('','16004','2',NULL,'2016-02-28'),  -- 26 -- Car Space 
    ('','16002',NULL,'4','2016-02-28'),  -- 27 -- Sport Facilities 
    ('','16002','13',NULL,'2016-02-28'), -- 28 -- Car Space 
    ('','16003',NULL,'3','2016-02-28'),  -- 29 -- Sport Facilities 
    ('','16004','2',NULL,'2016-02-28'),  -- 30 -- Car Space 
    ('','16004',NULL,'4','2016-02-28'),  -- 31 -- Sport Facilities 
    ('','16003',NULL,'5','2016-02-28'),  -- 32 -- Sport Facilities 
    ('','16001',NULL,'2','2016-02-28'),  -- 33 -- Sport Facilities 
    ('','16004',NULL,'10','2016-02-28'), -- 34 -- Sport Facilities 
    ('','16003','6',NULL,'2016-02-29'),  -- 35 -- Car Space 
    ('','16003',NULL,'11','2016-02-29'), -- 36 -- Sport Facilities 
    ('','16004',NULL,'8','2016-02-29'),  -- 37 -- Sport Facilities 
    ('','16004','2',NULL,'2016-02-29'),  -- 38 -- Car Space 
    ('','16001',NULL,'4','2016-02-29'),  -- 39 -- Sport Facilities 
    ('','16004',NULL,'6','2016-03-01'),  -- 40 -- Sport Facilities 
    ('','16003','6',NULL,'2016-03-01'),  -- 41 -- Car Space 
    ('','16002',NULL,'5','2016-03-01'),  -- 42 -- Sport Facilities 
    ('','16003',NULL,'3','2016-03-02'),  -- 43 -- Sport Facilities 
    ('','16001',NULL,'7','2016-03-02'),  -- 44 -- Sport Facilities 
    ('','16002',NULL,'4','2016-03-02'),  -- 45 -- Sport Facilities 
    ('','16004',NULL,'1','2016-03-02'),  -- 46 -- Sport Facilities 
    ('','16001',NULL,'12','2016-03-03'), -- 47 -- Sport Facilities 
    ('','16003','6',NULL,'2016-03-03'),  -- 48 -- Car Space 
    ('','16004',NULL,'9','2016-03-03'),  -- 49 -- Sport Facilities 
    ('','16003',NULL,'10','2016-03-03'), -- 50 -- Sport Facilities 
    ('','16002',NULL,'4','2016-03-04'),  -- 51 -- Sport Facilities 
    ('','16004',NULL,'8','2016-03-04'),  -- 52 -- Sport Facilities 
    ('','16003',NULL,'6','2016-03-05'),  -- 53 -- Sport Facilities 
    ('','16004',NULL,'13','2016-03-05'), -- 54 -- Sport Facilities 
    ('','16002',NULL,'8','2016-03-05'),  -- 55 -- Sport Facilities 
    ('','16001',NULL,'4','2016-03-05'),  -- 56 -- Sport Facilities 
    ('','16004',NULL,'5','2016-03-06'),  -- 57 -- Sport Facilities 
    ('','16003',NULL,'9','2016-03-06'),  -- 58 -- Sport Facilities 
    ('','16001',NULL,'11','2016-03-07'), -- 59 -- Sport Facilities 
    ('','16003',NULL,'5','2016-03-07')  -- 60 -- Sport Facilities 
;

来源

2016-03-26 Donald Chi Chung Fok

如何组合行？

看起来像引用车位的所有交易都有NULL体育设施参考，反之亦然。

查询是逐行完成的，当您将INNER JOIN事务处理为车位时，您将获取带有车位记录的车位引用的所有事务处理记录。所有其他交易都被过滤掉。

由于这些过滤的交易+汽车空间行都没有运动设施引用（全为NULL），所以当您将INNER JOIN添加到运动设施时，没有匹配的行，并且再次将不匹配的行过滤掉。这给你留下了一个空的结果集。

要从双INNER JOIN查询中获得任何结果，交易行将不得不引用（或链接）汽车空间和体育设施。

如果你想保留所有的交易行与他们的汽车空间或体育设施和一个NULLed的记录，无论哪一个都没有引用，你可以改变INNER JOIN到LEFT JOINs（只需将INNER替换为LEFT in你的最终查询）。

来源

2016-03-26 19:03:17 Arth

在这种情况下，我相信你会想使用UNION运算符。您没有在两个表中都匹配的事务ID，这就是您返回0行的原因。左/全连接也可能适用于您。

SELECT * FROM car_space INNER JOIN transaction ON car_space.carSpaceId = transaction.carSpaceId ORDER BY transactionId; 
UNION 
SELECT * FROM sport_facilities INNER JOIN transaction ON sport_facilities.sportFacilitiesId = transaction.sportFacilitiesId ORDER BY transactionId;

来源

2016-03-26 22:20:23

联盟不会在这里工作，在sports_facility表中有更多的列..它可能有助于一些调整，但两个表似乎相似。 – Arth

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