外鍵約束錯誤

Question

我想調試一個簡單的SQL數據庫。我不斷收到寫着

SQL query: 


CREATE TABLE Groups (
    groupId   int(11) NOT NULL AUTO_INCREMENT, 
    leaderId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    sportId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    groupName   varchar(255) COLLATE utf8_unicode_ci, 
    membersName  varchar(255) COLLATE utf8_unicode_ci, 
    groupDes   TEXT CHARACTER SET latin1 COLLATE latin1_general_cs, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (groupId), 
    FOREIGN KEY (sportId) REFERENCES Sports(sportId), 
    FOREIGN KEY (leaderId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 
MySQL said: Documentation 

#1215 - Cannot add foreign key constraint 

我知道，這是外鍵（sportId）參考文獻體育（sportId），行，因爲當我刪除它，我沒有錯誤，一切都很好錯誤。我的運動桌上可能有些問題，或者只是語法錯誤，但我似乎無法看到它。有人請告訴我我瘋了，它是一個簡單的語法問題。這是我正在寫的完整數據庫文件。

DROP DATABASE if EXISTS sqlfile; 
CREATE DATABASE sqlfile; 
USE sqlfile; 

DROP TABLE if EXISTS Users; 
CREATE TABLE Users (
    userId    int(11) NOT NULL AUTO_INCREMENT, 
    userName   varchar (255) UNIQUE NOT NULL COLLATE utf8_unicode_ci, 
    password   varchar(255) COLLATE utf8_unicode_ci, 
    firstName   varchar(255) COLLATE utf8_unicode_ci, 
    lastName   varchar(255) COLLATE utf8_unicode_ci, 
    tel    char(10) COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Groups (
    groupId   int(11) NOT NULL AUTO_INCREMENT, 
    leaderId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    sportId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    groupName   varchar(255) COLLATE utf8_unicode_ci, 
    membersName  varchar(255) COLLATE utf8_unicode_ci, 
    groupDes   TEXT CHARACTER SET latin1 COLLATE latin1_general_cs, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (groupId), 
    FOREIGN KEY (sportId) REFERENCES Sports(sportId), 
    FOREIGN KEY (leaderId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Members (
    memberId   int(11) NOT NULL AUTO_INCREMENT, 
    groupId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    userId    int(11) NOT NULL COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (memberId), 
    FOREIGN KEY (groupId) REFERENCES Groups(groupId), 
    FOREIGN KEY (userId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Sports (
    sportId   int(11) NOT NULL AUTO_INCREMENT, 
    sportName   varchar(255) COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (sportId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

Answer 1

您需要首先創建你的運動表，以便有成羣表的外鍵參考

DROP TABLE if EXISTS Users; 
CREATE TABLE Users (
.... 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 
CREATE TABLE Sports (
.... 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 
CREATE TABLE Groups (
.... 
    FOREIGN KEY (sportId) REFERENCES Sports(sportId), 
    FOREIGN KEY (leaderId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Members (
.... 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

DEMO

Answer 2

從檢查MySQL的轉儲輸出....

/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */; 

[your CREATEs here] 

/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */; 

除了單獨添加約束，這是我所知的唯一的其他方法甚至創建以某種循環或互惠方式相互引用的表格（而不是您的結構）。

Answer 3

您需要在組之前創建體育桌，或者在您有體育桌後在最後添加約束。

DROP DATABASE if EXISTS classbash; 
CREATE DATABASE classbash; 
USE classbash; 

DROP TABLE if EXISTS Users; 
CREATE TABLE Users (
    userId    int(11) NOT NULL AUTO_INCREMENT, 
    userName   varchar (255) UNIQUE NOT NULL COLLATE utf8_unicode_ci, 
    password   varchar(255) COLLATE utf8_unicode_ci, 
    firstName   varchar(255) COLLATE utf8_unicode_ci, 
    lastName   varchar(255) COLLATE utf8_unicode_ci, 
    tel    char(10) COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Sports (
    sportId   int(11) NOT NULL AUTO_INCREMENT, 
    sportName   varchar(255) COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (sportId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Groups (
    groupId   int(11) NOT NULL AUTO_INCREMENT, 
    leaderId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    sportId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    groupName   varchar(255) COLLATE utf8_unicode_ci, 
    membersName  varchar(255) COLLATE utf8_unicode_ci, 
    groupDes   TEXT CHARACTER SET latin1 COLLATE latin1_general_cs, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (groupId), 
    FOREIGN KEY (sportId) REFERENCES Sports(sportId), 
    FOREIGN KEY (leaderId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE Members (
    memberId   int(11) NOT NULL AUTO_INCREMENT, 
    groupId   int(11) NOT NULL COLLATE utf8_unicode_ci, 
    userId    int(11) NOT NULL COLLATE utf8_unicode_ci, 
    dateCreated TIMESTAMP DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (memberId), 
    FOREIGN KEY (groupId) REFERENCES Groups(groupId), 
    FOREIGN KEY (userId) REFERENCES Users(userId) 
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;