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mysql - 内部连接 ​​3 表

coder 2023-10-03 原文

我的数据库中有 6 个表 .现在我想加入 car_space、transaction 和 sport_facilities。但是，我遇到了问题。

当我分别使用这两个sql命令时，这两个命令也可以运行，并且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，我将它们组合成一个命令。

-- 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;

虽然可以运行，但是没有结果或显示记录。

我想做的是当我键入一个transactionId时，数据库可以找到在哪个表(car_space/sport_facilities)中的记录。 例如: 我输入 WHERE transactionId = 1 可以搜索数据库，这是来自 sport_facilities 表而不是 car_space。

谢谢。这里有一些代码供引用。

    -- 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','mkding@yahoo.com','98626229'),
    ('','637ED500','Emma','Dai','F','1972-06-15','D5060339','emmadai@yahoo.com.hk','62937453'),
    ('','B3895A02','Brinsley','Au','F','1984-02-24','P8172327','da224@live.hk','91961624'),
    ('','E32F3702','Eric','Fong','M','1990-04-15','Y1129323','ericfong0415@gmail.com','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
;

最佳答案

您希望如何组合行？

看起来您所有引用车位的交易都有一个 NULL 体育设施引用，反之亦然。

查询是逐行完成的，当您仅对车位进行 INNER JOIN 事务时，您将获得所有带有车位引用和车位记录的交易记录。所有其他交易都被过滤掉。

由于这些过滤的事务 + 车位行都没有体育设施引用(全部为 NULL)，当您随后将 INNER JOIN 添加到体育设施时，没有匹配的行，并且再次过滤掉不匹配的行。这会留下一个空的结果集。

要从双重 INNER JOIN 查询返回任何结果，事务行必须引用(或链接)一个车位和一个体育设施。

如果您想保留所有交易行及其车位或体育设施以及未引用的 NULLed 记录，您可以将 INNER JOIN 更改为 LEFT JOIN(只需将 INNER 替换为 LEFT最终查询)。

关于mysql - 内部连接 ​​3 表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36239226/

mysql内部392016NULL

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