Oracle 创建 table 无效名称/约束

Question

尝试在 SQL 中创建 table 时，我在 SQL 命令中遇到错误。以下是我的命令：

CREATE TABLE Registration
(
registrationID varchar2(5) NOT NULL CONSTRAINT registrationID PRIMARY KEY,
competitionID varchar2(5) NOT NULL CONSTRAINT competitionID REFERENCES Competition(competitionID),
competitorID varchar2(5) NOT NULL CONSTRAINT competitorID REFERENCES Competitor(competitorID),
categoryType varchar2(6) NOT NULL,
entryFeeStatus char(1) NOT NULL,
creditCardNumber number(16),
datePaid date

);

我的 competitionID 是 Competition table 的主键。 我的 competitorID 是 Competitor table.

的主键

显示的错误是：

Error report -
SQL Error: ORA-02264: name already used by an existing constraint
02264. 00000 -  "name already used by an existing constraint"
*Cause:    The specified constraint name has to be unique.
*Action:   Specify a unique constraint name for the constraint.

我可以知道我应该在声明中更改什么吗？谢谢。

---

以下是我创建的竞赛和竞争对手 table：

CREATE TABLE Competition
(
competitionID varchar2(5) NOT NULL CONSTRAINT competitionID PRIMARY KEY,
timePlanned date NOT NULL,
country varchar2(50) NOT NULL,
city varchar2(50),
address varchar2(50),
entryFee number(4) NOT NULL
);

CREATE TABLE Competitor
(
competitorID varchar2(5) NOT NULL CONSTRAINT competitorID PRIMARY KEY,
firstName varchar2(9) NOT NULL,
lastName varchar2(9) NOT NULL,
dateOfBirth date NOT NULL,
nationality varchar2(12),
gender varchar2(1) NOT NULL,
lifetimeRanking number(6),
totalPrizeMoney number(6)
);

Answer 1

您混淆了指定外键的两种不同方式。并且有一个额外的逗号。

CREATE TABLE Registration
(
registrationID varchar2(5) NOT NULL CONSTRAINT registrationID PRIMARY KEY,
competitionID varchar2(5) NOT NULL CONSTRAINT competitionIDfk  REFERENCES Competition(competitionID),
competitorID varchar2(5) NOT NULL CONSTRAINT competitorIDfk  REFERENCES Competitor(competitorID)
)

可以按列指定外键：

columnname datatype CONSTRAINT constraintname REFERENCES tablename [ (column) ]

或根据 table:

CONSTRAINT constraintname FOREIGN KEY (column-list) REFERENCES tablename [ (column-list) ]

Answer 2

BOOLEAN 是无效的 SQL 类型。使用 NUMBER(1) 与 0 和 1，CHAR(1) 或 VARCHAR2(1) 与 'Y' 和 'N' 值或其他代理表示。