如何向有外键约束的字表中插入记录？
我在mysql中建了两个表
mysql> describe room;
+--------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+----------+------+-----+---------+-------+
| name | char(20) | NO | PRI | NULL | |
| doctor | char(20) | NO | | NULL | |
+--------+----------+------+-----+---------+-------+
2 rows in set (0.07 sec)
字表是
mysql> describe guahao;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| name | char(20) | NO | PRI | NULL | |
| sex | char(10) | NO | | NULL | |
| age | char(10) | NO | | NULL | |
| room | char(20) | NO | MUL | NULL | |
+-------+----------+------+-----+---------+-------+
4 rows in set (0.00 sec)
其中外键是room，on delete cascade on update cascade
我在命令行中向字表中插入数据没有问题,结果是
mysql> insert into guahao values
-> ('小张','男','30','皮肤科');
Query OK, 1 row affected (0.04 sec)
mysql> select * from guahao;
+--------+-----+-----+-----------+
| name | sex | age | room |
+--------+-----+-----+-----------+
| 王八 | 女 | 60 | 内科 |
| 钱二 | 男 | 40 | 脑科 |
| 赵一 | 男 | 20 | 五官科 |
| 孙三 | 女 | 35 | 骨科 |
| 寂寞 | 男 | 22 | 骨科 |
| 小张 | 男 | 30 | 皮肤科 |
| 小明 | 男 | 25 | 脑科 |
| 李四 | 男 | 30 | 皮肤科 |
+--------+-----+-----+-----------+
9 rows in set (0.00 sec)
但是我用PHP的时候，同样的插入语句，却会报错，错误信息如下：
Cannot add or update a child row: a foreign key constraint fails (`clinic`., CONSTRAINT `#sql-9e_13_ibfk_1` FOREIGN KEY (`room`) REFERENCES `room` (`name`) ON DELETE CASCADE ON UPDATE CASCADE)
请大神帮我看看问题在哪！跪求！哭了，问过一次，没解决问题。
回复讨论(解决方案)
为什么这个问题没有人回复？不是很难的问题啊
1、你的操作系统？
2、你的程序使用的字符集？
3、为了给帮助你的人提供便利，你应该给出
a、建表的 sql 指令
b、供测试用的 php 代码
吼吼,快来人解答~~
1、你的操作系统？
2、你的程序使用的字符集？
3、为了给帮助你的人提供便利，你应该给出
a、建表的 sql 指令
b、供测试用的 php 代码
1. 操作系统是MAC OS X
2. 字符集是
mysql> show variables like 'character%';
+--------------------------+--------------------------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------------------------+
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/local/mysql-5.1.63-osx10.6-x86_64/share/charsets/ |
+--------------------------+--------------------------------------------------------+
8 rows in set (0.08 sec)
用于插入数据库的数据是从一个编码为UTF-8的HTML页面用post方法传到一个编码同样为UTF-8的PHP文件。
3.
建表的sql指令是在终端输入的 如下
mysql> create table room(name char(20) not null primary key, doctor char(20) not null) type=innodb;
Query OK, 0 rows affected, 1 warning (0.05 sec)
mysql> create table guahao -> (name char(20) not null primary key, -> sex char(10) not null,
-> age char(10) not null,
-> room char(20) not null,
-> foreign key(room) references room(name) on delete cascade on update cascade)
-> type=innodb;
Query OK, 0 rows affected, 1 warning (0.41 sec)
PHP代码是
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=GB18030"><title>医院门诊挂号系统</title><style type="text/css"> #table { margin-right: auto; margin-left: auto; }</style></head><body style="text-align: center"><?php$pname=$_POST['pname'];$psex=$_POST['psex'];$page=$_POST['page'];$room=$_POST['room'];if (empty($pname)||empty($psex)||empty($page)){?><p style="text-align:center">请输入完整的患者信息！</p><form method="post" action="Guahao.php"><table id="table"><tr><td>姓名：</td><td><input type="text" id="pname" /></td><td>性别：</td><td><input type="text" id="psex" /></td></tr><tr><td>年龄：</td><td><input type="text" id="page" /></td><td>科室：</td><td><input type="text" id="room" /></td></tr></table><input type="reset" value="重置" id="reset" style="width:100px;height:20px" /><input type="submit" value="挂号" id="submit" style="width:100px;height:20px" /></form><?php}else{ $db = new mysqli('127.0.0.1','clinicadmin','clinicadmin','clinic'); if (mysqli_connect_errno()) { echo "无法连接数据库，请稍后重试。"; exit; } $query = "insert into guahao values ('".$pname."', '".$psex."', '".$page."', '".$room."')"; $result = $db->query($query); if (!$result) { echo $db->error; echo"无法登陆！"; exit; } else { echo"<p>挂号成功！</p>"; } $db->close();?><a href="guahao.html">继续挂号</a><?php} ?></body></html> 字符集问题！
1、你的表中没有给字符类型字段设置字符集（默认 latin1）
2、你在连接数据库后没有声明字符集（缺少 set names 指令）
3、你说你使用了 utf-8 字符集，而程序中有 charset=GB18030
实际是使用了gbk 字符集
GB18030 是正式的国家标准，目前尚未在计算机中实现。所以实际使用的是其子集--GBK
忽略外键：SET FOREIGN_KEY_CHECKS = 0
字符集问题！
1、你的表中没有给字符类型字段设置字符集（默认 latin1）
2、你在连接数据库后没有声明字符集（缺少 set names 指令）
3、你说你使用了 utf-8 字符集，而程序中有 charset=GB18030
实际是使用了gbk 字符集
GB18030 是正式的国家标准，目前尚未在计算机中实现。所以实际使用的是其子集--GBK
那个问题我已经解决了，就是字符集问题，谢谢斑竹大神！这么多天才来结贴
字符集问题！
1、你的表中没有给字符类型字段设置字符集（默认 latin1）
2、你在连接数据库后没有声明字符集（缺少 set names 指令）
3、你说你使用了 utf-8 字符集，而程序中有 charset=GB18030
实际是使用了gbk 字符集
GB18030 是正式的国家标准，目前尚未在计算机中实现。所以实际使用的是其子集--GBK
……
版主你好，我用跟楼主一样的建表命令建表，但是不能插入和楼主一样的数据，提示foreign constraints fails，请问该怎么解决呢？
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