Oracle SQL 约束，输入的名称必须是成员

Question

我已经创建了一个网球俱乐部数据库。此数据库包含以下 tables:

玩家table

CREATE TABLE player
(
  member_id INT PRIMARY KEY NOT NULL, 
  member_name VARCHAR2(70) NOT NULL,
  date_of_birth DATE,
  member_address VARCHAR2(300),
  contact_number INT NOT NULL,
  gender VARCHAR2(1) NOT NULL CHECK(gender IN('f','m')),
  club_seeding INT NOT NULL,
  county_seeding INT NOT NULL,
  renewal_date DATE,
  m_type VARCHAR(9) NOT NULL CHECK(m_type IN('junior','student', 'senior', 'family', 'associate'))
);

这包括网球俱乐部的成员。

然后是团队 table

CREATE TABLE team
(
  team_id INT PRIMARY KEY NOT NULL,
  club_seeding INT,
  county_seeding INT,
  player1 VARCHAR2(70) NOT NULL,
  player2 VARCHAR2(70) NOT NULL,
  team_name VARCHAR2(145) NOT NULL
);

用于输入2名选手组成双打队伍。

我的问题是如何创建一个约束，只允许来自玩家 table 的玩家（member_name）进入团队 table?

Answer 1

您需要创建外键约束请参阅文档 here

但在您的示例中，您需要将 player1 和 player2 列的类型从 varchar 更改为 int:

sample of alter table statements

-- Create foreign key constraints 
alter table TEAM
  add constraint fk_team_player_1 foreign key (PLAYER1)
  references player (MEMBER_ID);

alter table TEAM
  add constraint fk_team_player_2 foreign key (PLAYER2)
  references player (MEMBER_ID);

在 table

中创建 FK 约束的示例

CREATE TABLE team
(
  team_id INT PRIMARY KEY NOT NULL,
  club_seeding INT,
  county_seeding INT,
  player1 INT NOT NULL,
  player2 INT NOT NULL,
  team_name VARCHAR2(145) NOT NULL

,constraint fk_team_player_1 foreign key (PLAYER1)
  references player (MEMBER_ID)
,constraint fk_team_player_2 foreign key (PLAYER2)
  references player (MEMBER_ID)  
);

if you want to use member names as PK

CREATE TABLE player
( 
  member_name VARCHAR2(70) PRIMARY KEY NOT NULL,
  date_of_birth DATE,
  member_address VARCHAR2(300),
  contact_number INT NOT NULL,
  gender VARCHAR2(1) NOT NULL CHECK(gender IN('f','m')),
  club_seeding INT NOT NULL,
  county_seeding INT NOT NULL,
  renewal_date DATE,
  m_type VARCHAR(9) NOT NULL CHECK(m_type IN('junior','student', 'senior', 'family', 'associate'))
);

CREATE TABLE team
(
  team_id INT PRIMARY KEY NOT NULL,
  club_seeding INT,
  county_seeding INT,
  player1 VARCHAR2(70) NOT NULL,
  player2 VARCHAR2(70) NOT NULL,
  team_name VARCHAR2(145) NOT NULL

,constraint fk_team_player_1 foreign key (PLAYER1)
  references player (member_name)
,constraint fk_team_player_2 foreign key (PLAYER2)
  references player (member_name)  
);

Oracle SQL 约束，输入的名称必须是成员

Oracle SQL constraint, name entered must be a member

sql

oracle

constraints