內部連接3表

我在我的數據庫中有6個表 booking_system 。現在我想要加入car_space，transaction和sport_facilities。但是，我遇到了問題。內部連接3表

當我分別使用這兩個sql命令時，這些命令也可以運行，我可以得到我想要的結果。

-- 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;

然後，我將它們合併爲一個命令。

-- 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;

雖然這可以運行，但沒有結果或記錄顯示。

我想要做的是當我鍵入一個transactionId時，數據庫可以被找到記錄在哪個表（car_space/sport_facilities）中。例如：我輸入WHERE transactionId = 1 數據庫可以搜索這是從sport_facilities表，而不是car_space。

謝謝。這裏有一些代碼供參考。

-- 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 
;

來源

2016-03-26 Donald Chi Chung Fok

如何組合行？

看起來像引用車位的所有交易都有NULL體育設施參考，反之亦然。

查詢是逐行完成的，當您將INNER JOIN事務處理爲車位時，您將獲取帶有車位記錄的車位引用的所有事務處理記錄。所有其他交易都被過濾掉。

由於這些過濾的交易+汽車空間行都沒有運動設施引用（全爲NULL），所以當您將INNER JOIN添加到運動設施時，沒有匹配的行，並且再次將不匹配的行過濾掉。這給你留下了一個空的結果集。

要從雙INNER JOIN查詢中獲得任何結果，交易行將不得不引用（或鏈接）汽車空間和體育設施。

如果你想保留所有的交易行與他們的汽車空間或體育設施和一個NULLed的記錄，無論哪一個都沒有引用，你可以改變INNER JOIN到LEFT JOINs（只需將INNER替換爲LEFT in你的最終查詢）。

來源

2016-03-26 19:03:17 Arth

在這種情況下，我相信你會想使用UNION運算符。您沒有在兩個表中都匹配的事務ID，這就是您返回0行的原因。左/全連接也可能適用於您。

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;

來源

2016-03-26 22:20:23

聯盟不會在這裏工作，在sports_facility表中有更多的列..它可能有助於一些調整，但兩個表似乎相似。 – Arth

回答

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