我正在尝试重新定义我的数据库设计，添加一些额外的表，因此在我的表 Departaments 和 Jobs 中没有重复的名称......
但是我收到了与外键有关的错误 121，你能解释一下为什么会出现这个问题吗？
我正在尝试做这样的事情，但在 sqlfiddle 中没有运气，我目前正在工作
CREATE TABLE Employee(
EmployeeID INTEGER NOT NULL PRIMARY KEY,
Name VARCHAR(30) NOT NULL,
Sex CHAR(1) NOT NULL,
Address VARCHAR(80) NOT NULL,
Security VARCHAR(15) NOT NULL
);
CREATE TABLE Departments (
DeptID INTEGER NOT NULL PRIMARY KEY,
DeptName VARCHAR(30) NOT NULL
);
如果我取消注释代码，我得到 Schema Creation Failed: Can't create table 'db_2_2bf4a.project-employee' (errno: 121)：
CREATE TABLE `Dept-Employee`(
EmployeeID INTEGER NOT NULL,
DeptID INTEGER NOT NULL,
CONSTRAINT fk_DeptID FOREIGN KEY (DeptID) REFERENCES Departments(DeptID),
CONSTRAINT fk_EmployeeID FOREIGN KEY (EmployeeID) REFERENCES Employee(EmployeeID)
);
CREATE TABLE `Dept-Manager`(
EmployeeID INTEGER NOT NULL,
DeptID INTEGER NOT NULL,
CONSTRAINT fk_DeptID FOREIGN KEY (DeptID) REFERENCES Departments(DeptID),
CONSTRAINT fk_EmployeeID FOREIGN KEY (EmployeeID) REFERENCES Employee(EmployeeID)
);
CREATE TABLE Jobs (
JobID INTEGER NOT NULL PRIMARY KEY,
JobName VARCHAR(30) NOT NULL,
JobSalary DOUBLE(15,3) NOT NULL default '0.000',
JobSalaryperDay DOUBLE(15,3) NOT NULL default '0.000',
DeptID INTEGER NOT NULL
);
CREATE TABLE `Jobs-Employee`(
EmployeeID INTEGER NOT NULL,
JobID INTEGER NOT NULL,
CONSTRAINT fk_JobID FOREIGN KEY (JobID) REFERENCES Jobs(JobID),
CONSTRAINT fk_EmployeeID FOREIGN KEY (EmployeeID) REFERENCES Employee(EmployeeID)
);
CREATE TABLE Project(
ProjectID INTEGER NOT NULL PRIMARY KEY,
ProjectDesc VARCHAR(200) NOT NULL,
StartDate DATE NOT NULL,
EndDate DATE NOT NULL,
DaysOfWork INTEGER NOT NULL,
NoEmployees INTEGER NOT NULL,
EstimatedCost DOUBLE(15,3) NOT NULL default '0.000',
RealCost DOUBLE(15,3) NOT NULL default '0.000'
);
CREATE TABLE `Project-Employee`(
ProjectID INTEGER NOT NULL,
EmployeeID INTEGER NOT NULL,
Note VARCHAR(200),
DaysWork INTEGER NOT NULL,
CONSTRAINT fk_ProjectID FOREIGN KEY (ProjectID) REFERENCES Project(ProjectID),
CONSTRAINT fk_EmployeeID FOREIGN KEY (EmployeeID) REFERENCES Employee(EmployeeID)
);
所以在我不知道这个查询是否正确之后
INSERT INTO `Departments` VALUES (1, 'Outsourcing');
INSERT INTO `Departments` VALUES (2, 'Technician');
INSERT INTO `Departments` VALUES (3, 'Administrative');
INSERT INTO `Jobs` VALUES (1, 'welder' ,500.550,16.7 ,2);
INSERT INTO `Jobs` VALUES (2, 'turner' ,500.100,16.67,2);
INSERT INTO `Jobs` VALUES (3, 'assistant' ,650.100,21.67,2);
INSERT INTO `Jobs` VALUES (4, 'supervisor',800.909,26.70,3);
INSERT INTO `Jobs` VALUES (5, 'manager' ,920.345,30.68,3);
INSERT INTO `Jobs` VALUES (6, 'counter' ,520.324,17.35,1);
INSERT INTO `Dept-Employee` (10,1);
INSERT INTO `Dept-Employee` (10,2);
INSERT INTO `Dept-Employee` (10,3);
INSERT INTO `Dept-Employee` (10,1);
INSERT INTO `Dept-Employee` (10,3);
INSERT INTO `Jobs-Employee` (10,3);
INSERT INTO `Jobs-Employee` (10,3);
INSERT INTO `Jobs-Employee` (10,4);
INSERT INTO `Jobs-Employee` (10,6);
INSERT INTO `Jobs-Employee` (10,5);
INSERT INTO `Employee` VALUES (10, 'Joe', 'M', 'Anywhere', '927318344');
INSERT INTO `Employee` VALUES (20, 'Moe', 'M', 'Anywhere', '827318322');
INSERT INTO `Employee` VALUES (30, 'Jack', 'M', 'Anywhere', '927418343');
INSERT INTO `Employee` VALUES (40, 'Marge','F', 'Evererre', '127347645');
INSERT INTO `Employee` VALUES (50, 'Greg' ,'M', 'Portland', '134547633');
INSERT INTO `Project` VALUES (1, 'The very first', '2008-7-04' , '2008-7-24' , 20, 5, 3000.50, 2500.00);
INSERT INTO `Project` VALUES (2, 'Second one pro', '2008-8-01' , '2008-8-30' , 30, 5, 6000.40, 6100.40);
INSERT INTO `Project-Employee` VALUES (1, 10, 'Worked all days' , 20);
INSERT INTO `Project-Employee` VALUES (1, 20, 'Worked just in defs', 11);
INSERT INTO `Project-Employee` VALUES (1, 30, 'Worked just in defs', 17);
INSERT INTO `Project-Employee` VALUES (1, 40, 'Contability ' , 8);
INSERT INTO `Project-Employee` VALUES (1, 50, 'Managed the project', 8);