php - mysql php不能取外键值

Question

您好，我的 php 代码有问题。招聘系统有 3 个表。

CREATE TABLE IF NOT EXISTS `members` (
   `uid` int(11) NOT NULL AUTO_INCREMENT,
   `username` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
   `password` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
   `cpassword` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
   `email` varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
   `role` varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
   PRIMARY KEY (`uid`)'
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=60 ;   

候选表：

CREATE TABLE IF NOT EXISTS `candidate` (
  `fullname` varchar(35) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `webpage` varchar(150) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `tel` int(35) NOT NULL,
  `nationality` varchar(35) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `position` varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `interviewed` varchar(30) NOT NULL DEFAULT 'No',
  `rating` varchar(30) NOT NULL,
  `c_id` int(11) NOT NULL AUTO_INCREMENT,
  `uid` int(11) NOT NULL,
  PRIMARY KEY (`c_id`),
  KEY `uid` (`uid`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=135 ;

学术表：

CREATE TABLE IF NOT EXISTS `academic_candidate` (    
    `degree` varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `exp_years` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `comment1` varchar(300) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `proposed_positions` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `research_years` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `comment2` varchar(300) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `department` varchar(25) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
    `a_id` int(25) NOT NULL AUTO_INCREMENT,
    `uid` int(11) NOT NULL,
    `c_id` int(11) NOT NULL,
    PRIMARY KEY (`a_id`),
    UNIQUE KEY `id` (`a_id`),
    KEY `uid` (`uid`),
    KEY `c_d` (`c_id`),
    KEY `c_id` (`c_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=40 ;`

-- 表格约束academic_candidate

ALTER TABLEAcademic_candidate ADD CONSTRAINTAcademic_candidate_ibfk_1 FOREIGN KEY (uid) REFERENCES成员(uid ) ON DELETE CASCADE ON UPDATE CASCADE, ADD CONSTRAINTAcademic_candidate_ibfk_2 FOREIGN KEY (c_id) REFERENCES候选人(c_id) ON DELETE CASCADE ON UPDATE CASCADE;

--

-- 表格约束candidate

ALTER TABLE候选人 ADD CONSTRAINTcandidate_ibfk_1 FOREIGN KEY (uid) REFERENCES成员(uid) ON DELETE CASCADE ON UPDATE CASCADE;

--

现在，我使用此查询将值存储在表 Academic_candidate

session_start();

    $query = "SELECT * FROM academic_candidate WHERE degree = '$degree'";
$result = mysql_query($query);
$count  = mysql_num_rows($result);

if($count > 0){ 
    echo "You ALready complete the form </br>";
    header("Location:../candidate/candidate_index.php");
}
else{
        $degree =($_POST['degree']);
        $exp_years = ($_POST['exp_years']);
        $comment1 = ($_POST['comment1']);
        $proposed_positions = ($_POST['proposed_positions']);
    $research_years=($_POST['research_years']);
    $comment2=($_POST['comment2']);
    $department=($_POST['department']);

   $uid=($_SESSION['uid']);


    $query1 = "INSERT INTO academic_candidate

                (degree,exp_years,comment1,proposed_positions,research_years,comment2,department,uid,c_id)
                SELECT
                 '$degree','$exp_years','$comment1','$proposed_positions','$research_years','$comment2','$department','$uid','$c_id'
                    FROM  candidate         
                 WHERE  uid='$uid' AND c_id='$c_id'  ";


    $result = mysql_query($query1);

    if(!$result){
        echo "Error";
        die (mysql_error());                                          
    }   

    else{
        header("Location:../candidate/view_application.php");
    }

}

我的问题是将所有值存储在表 Academic_candidate 表上，但 c_id 为 0 。我能做些什么来获取candidate.c_id？

Answer 1

您正在将文字值传递给您的INSERT INTO语句。

考虑差异：

SELECT 'bar' FROM foo;

SELECT bar FROM foo;

这是关于 SQLFiddle 的演示。

查看您的查询：

SELECT '$degree'

不一样：

SELECT degree

其中一个只是简单地回显您传入的任何值，另一个实际上是从数据库中选择一列。