将数据添加到表时出现 MySQL 错误 1452

Question

尝试通过 MySQL Workbench 导入数据时出现以下错误：

Preparing...
Importing DataInputs.sql...
Finished executing script
ERROR 1452 (23000) at line 6: Cannot add or update a child row: a foreign key constraint fails (`nsldatabase`.`player`, CONSTRAINT `playsFor` FOREIGN KEY (`player_ID`) REFERENCES `team` (`team_ID`))
Operation failed with exitcode 1

我正在通过两个不同的 SQL 脚本创建数据库。 一个创建表，另一个导入数据。 我最初认为某些外键没有正确定义，但似乎它们都设置正确。 任何帮助都会很棒。 请参阅以下两个文件：

这是 NLSStructure.sql 文件：

DROP DATABASE IF EXISTS NSLdatabase;

CREATE SCHEMA IF NOT EXISTS NSLdatabase;
USE NSLdatabase;



CREATE TABLE player (
  player_ID int NOT NULL,
  player_Name text NOT NULL,
  player_Position text NOT NULL,
  player_Skills int NOT NULL,
  team_ID int NOT NULL,
  CONSTRAINT playerPK PRIMARY KEY (player_ID)
);

CREATE TABLE history (
  history_ID int NOT NULL,
  player_ID int NOT NULL,
  history_Desc text NOT NULL,
  history_sDate text NOT NULL,
  history_eDate text NOT NULL,
  CONSTRAINT recordPK PRIMARY KEY (history_ID, player_ID)
);

CREATE TABLE field (
  field_ID int NOT NULL,
  field_Name text NOT NULL,
  field_Location text NOT NULL,
  CONSTRAINT fieldPK PRIMARY KEY (field_ID)
);

CREATE TABLE team (
  team_ID int NOT NULL,
  team_Name text NOT NULL,
  team_City text NOT NULL,
  field_ID int NOT NULL,
  captain_ID int NOT NULL,
  team_coach text NOT NULL,
  CONSTRAINT teamPK PRIMARY KEY (team_ID)
);

CREATE TABLE matches (
  matches_ID int NOT NULL,
  matches_Date text NOT NULL,
  matches_Score text NOT NULL,
  matches_Winner text NOT NULL,
  field_ID int NOT NULL,
  teamHost_ID int NOT NULL,
  teamGuest_ID int NOT NULL,
  CONSTRAINT matchesPK PRIMARY KEY (matches_ID)
);

CREATE TABLE goal (
  goal_ID int NOT NULL,
  goal_Time int NOT NULL,
  matches_ID int NOT NULL,
  player_ID int NOT NULL,
  CONSTRAINT goalPK PRIMARY KEY (goal_ID, matches_ID, player_ID)
);

ALTER TABLE team
  ADD CONSTRAINT capitanRel FOREIGN KEY (captain_ID)
  REFERENCES player (player_ID);

ALTER TABLE team
  ADD CONSTRAINT playedOnField FOREIGN KEY (field_ID)
  REFERENCES field (field_ID);

ALTER TABLE player
  ADD CONSTRAINT playsFor FOREIGN KEY (player_ID)
  REFERENCES team (team_ID);

ALTER TABLE history
  ADD CONSTRAINT hasRel FOREIGN KEY (player_ID)
  REFERENCES player (player_ID);

ALTER TABLE goal
  ADD CONSTRAINT scoredBy FOREIGN KEY (player_ID)
  REFERENCES player (player_ID);

ALTER TABLE goal
  ADD CONSTRAINT scoredIn FOREIGN KEY (matches_ID)
  REFERENCES matches (matches_ID);

ALTER TABLE matches
  ADD CONSTRAINT playedOn FOREIGN KEY (field_ID)
  REFERENCES field (field_ID);

ALTER TABLE matches
  ADD CONSTRAINT playedHost FOREIGN KEY (teamHost_ID)
  REFERENCES team (team_ID);

ALTER TABLE matches
  ADD CONSTRAINT playedGuest FOREIGN KEY (teamGuest_ID)
  REFERENCES team (team_ID);

这是 DataInputs.sql 文件：

USE NSLdatabase;

INSERT INTO player
  VALUES
  (1, "Paxton Pomykal", "Midfielder", 7.5, 1);

INSERT INTO history
  VALUES
  (1, 3, "US 20 Squad", "11/27/2003", "12/19/2003");

INSERT INTO field
  VALUES
  (1, "Dicks Sporting Goods Park", "Commerce City, CO");

INSERT INTO team
  VALUES
  (2, "Colorado Rapids", "Denver, CO", 1, 3, "Robin Fraser");

INSERT INTO matches
  VALUES
  (1, "01/08/2019", "0-1", 2, 1, 1, 2);

INSERT INTO goal
  VALUES
  (1, 32, 1, 19);

Answer 1

您没有以正确的顺序插入数据。 父行需要在子行之前创建，因此不会违反外键约束。

因此，通常，您需要先在team行中创建行，然后再在player创建行。 基于相同的逻辑，您可能需要查看其他依赖项。

另一种方法是在插入数据后添加外键约束。 但是，我不一定建议：如果您的数据具有无效关系，您将无法创建外键。 反过来进行会更安全，因为会立即发出违规行的信号。