我正在尝试使用以下方法向表 ag 添加外键约束：
alter table ag
add foreign key fk_ag_protein1 (protein_PID) references protein (PID);
但我收到以下错误消息：
ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails
(`mux_new`.`#sql-884_3`, CONSTRAINT `#sql-884_3_ibfk_1` FOREIGN KEY (`protein_PID`)
REFERENCES `protein` (`PID`))"
为了获得更多详细信息，我检查了以下输出：
SHOW ENGINE INNODB STATUS\G
这是：
LATEST FOREIGN KEY ERROR
------------------------
TRANSACTION 193923, ACTIVE 0 sec inserting, thread declared inside InnoDB 4999
mysql tables in use 2, locked 2
5 lock struct(s), heap size 1248, 2 row lock(s), undo log entries 1
MySQL thread id 3, OS thread handle 0x1714, query id 143 localhost ::1 root copy
to tmp table
alter table ag
add foreign key fk_ag_protein1 (protein_PID) references protein (PID)
Foreign key constraint fails for table `mux_new`.`#sql-884_3`:
,
CONSTRAINT `#sql-884_3_ibfk_1` FOREIGN KEY (`protein_PID`) REFERENCES `protein
` (`PID`)
Trying to add in child table, in index `fk_ag_protein1` tuple:
DATA TUPLE: 2 fields;
0: len 4; hex 80000000; asc ;;
1: len 3; hex 002711; asc ' ;;
But in parent table `mux_new`.`protein`, in index `PRIMARY`,
the closest match we can find is record:
PHYSICAL RECORD: n_fields 1; compact format; info bits 0
0: len 8; hex 696e66696d756d00; asc infimum ;;
但我完全不明白这一点。表 ag 当前包含一些数据，但蛋白质没有。
关于我的问题可能是什么或我可以检查的事情的任何想法？
蛋白质表：
描述蛋白质输出：
+---------------------------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------------------+---------+------+-----+---------+-------+
| PID | int(11) | NO | PRI | NULL | |
| uniprot_UniprotAC | char(6) | YES | MUL | NULL | |
| pubmedhits_id | int(11) | YES | MUL | NULL | |
| internallyDefinedNames_id | int(11) | YES | MUL | NULL | |
| comment | int(11) | YES | MUL | NULL | |
+---------------------------+---------+------+-----+---------+-------+
显示创建表蛋白质输出：
CREATE TABLE `protein` (
`PID` int(11) NOT NULL,
`uniprot_UniprotAC` char(6) COLLATE utf8_unicode_ci DEFAULT NULL,
`pubmedhits_id` int(11) DEFAULT NULL,
`internallyDefinedNames_id` int(11) DEFAULT NULL,
`comment` int(11) DEFAULT NULL,
PRIMARY KEY (`PID`),
KEY `fk_protein_uniprot1_idx` (`uniprot_UniprotAC`),
KEY `fk_protein_pubmedhits1_idx` (`pubmedhits_id`),
KEY `fk_protein_internallyDefinedNames1_idx` (`internallyDefinedNames_id`),
KEY `fk_protein_comments1_idx` (`comment`),
CONSTRAINT `protein_ibfk_4` FOREIGN KEY (`uniprot_UniprotAC`) REFERENCES `uniprot` (`UniprotAC`),
CONSTRAINT `protein_ibfk_1` FOREIGN KEY (`comment`) REFERENCES `comments` (`idcomments`),
CONSTRAINT `protein_ibfk_2` FOREIGN KEY (`internallyDefinedNames_id`) REFERENCES `internallydefinednames` (`id`),
CONSTRAINT `protein_ibfk_3` FOREIGN KEY (`pubmedhits_id`) REFERENCES `pubmedhits` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
农业表：
描述 ag：
+-------------+--------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+--------------------------------+------+-----+---------+-------+
| Article_AID | mediumint(5) unsigned zerofill | NO | PRI | NULL | |
| Name | varchar(200) | YES | | NULL | |
| Form | varchar(150) | YES | | NULL | |
| Mw | varchar(40) | YES | | NULL | |
| Source | varchar(260) | YES | | NULL | |
| protein_PID | int(11) | YES | | NULL | |
+-------------+--------------------------------+------+-----+---------+-------+
显示创建表 ag：
`ag` (
`Article_AID` mediumint(5) unsigned zerofill NOT NULL,
`Name` varchar(200) COLLATE utf8_unicode_ci DEFAULT NULL,
`Form` varchar(150) COLLATE utf8_unicode_ci DEFAULT NULL,
`Mw` varchar(40) COLLATE utf8_unicode_ci DEFAULT NULL,
`Source` varchar(260) COLLATE utf8_unicode_ci DEFAULT NULL,
`protein_PID` int(11) DEFAULT NULL,
PRIMARY KEY (`Article_AID`),
KEY `fk_ag_Article1_idx` (`Article_AID`),
CONSTRAINT `fk_ag_Article1` FOREIGN KEY (`Article_AID`) REFERENCES `article` (`AID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci