[英]MySQL Primary Key as Foreign Key - Constraint error
假設我有3個表。
CREATE TABLE IF NOT EXISTS GROUP (
ID_GROUP INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
GROUP VARCHAR(50) NOT NULL,
INDEX(GROUP)
) ENGINE=INNODB DEFAULT CHARACTER SET = utf8 COLLATE = utf8_general_ci;)
CREATE TABLE IF NOT EXISTS USERZ (
ID CHAR(8) NOT NULL,
GROUP VARCHAR(50) NOT NULL,
FIRST_NAME VARCHAR(100) NULL DEFAULT NULL ,
LAST_NAME VARCHAR(100) NULL DEFAULT NULL,
DATE_CREATED TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
PASSWORD VARCHAR(8) NULL DEFAULT 'HELLOWORLD',
PRIMARY KEY (ID),
INDEX (ID),
INDEX (GROUP),
FOREIGN KEY (GROUP) REFERENCES GROUP (GROUP)
) ENGINE=INNODB DEFAULT CHARACTER SET = utf8 COLLATE = utf8_general_ci;)
CREATE TABLE IF NOT EXISTS WORKERS (
ID CHAR(8) NOT NULL PRIMARY KEY,
DATE_START TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
DATE_END TIMESTAMP NULL,
FOREIGN KEY (ID) REFERENCES USERZ (ID)
) ENGINE=INNODB DEFAULT CHARACTER SET = utf8 COLLATE = utf8_general_ci;)
我在表USERZ中插入數據沒有問題。 但是當涉及到向表WORKERS添加記錄時,我得到了錯誤消息:
mysql.connector.errors.IntegrityError:1452(23000):不能添加或更新子行,外鍵約束失敗( DATABASENAME
。 WORKERS
,約束WORKERS_ibfk_1
外鍵( ID
)參考文獻USERZ
( ID
))
我肯定知道這與WORKERS主鍵(ID)有關,是指USERZ(ID)。 即使我知道USERZ ID中存在USERZ ID,也不會允許我向WORKERS添加數據。 在下面的示例中,我知道USERZ表中存在“ XXXXXXX1”,因此我想能夠在WORKERS表中添加此用戶。
例如:
"INSERT INTO WORKERS (ID) VALUES ('XXXXXXX1') "
謝謝 !
您也不應將主鍵ID設置為外鍵。 重構成這樣
CREATE TABLE IF NOT EXISTS WORKERS (
ID CHAR(8) NOT NULL PRIMARY KEY,
USER_ID CHAR(8) NOT NULL,
DATE_START TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
DATE_END TIMESTAMP NULL,
FOREIGN KEY (USER_ID) REFERENCES USERZ (ID)
) ENGINE=INNODB DEFAULT CHARACTER SET = utf8 COLLATE = utf8_general_ci;)
然后您的插入內容應該是
INSERT INTO WORKERS (USER_ID) VALUES ('XXXXXXX1')
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