试图调试INNER JOIN cannundrum

Question

我正在使用一个较小的函数来尝试调试一个更大的函数的内部连接。我是一个很少使用连接经验的新手。事实上，我刚刚开始尝试使用两三天前的内连接作为我的第一次加入体验。较小的功能如下：

$data3 = '\'' . implode('\', \'', $posted_email) . '\''; 
echo "post email var dump: "; 
var_dump($posted_email); 
$exam_recordation = mysql_query("SELECT Student_email FROM exam WHERE partner_id IN (SELECT partner_id FROM exam WHERE Student_email = $data3) AND Student_email <> $data3"); 
echo "<br>recordation query: "; 
echo "SELECT Student_email FROM exam WHERE partner_id IN (SELECT partner_id FROM exam WHERE Student_email = $data3) AND Student_email <> $data3"; 
echo "<br>recordation var dump: "; 
var_dump($exam_recordation); 
echo "<table border=='1'> 
<tr> 
<th>Name</th> 
</tr>"; 
while ($fetch_record = mysql_fetch_array($exam_recordation)) 
{ 
    echo "<tr>"; 
    echo "<td>" . $fetch_record['Student_email'] . "</td>"; 
    echo "</tr>"; 
} 
echo "</table>"; 
//inner join should use the email of the partner out of $exam query to find their name and print it 
$name_query = mysql_query("SELECT DISTINCT student.name 
       FROM student 
       INNER JOIN exam ON student.email = exam.Student_email 
       WHERE student.email = $exam_recordation[Student_email]"); 
echo "<br><br>INNER JOIN query: "; 
echo "SELECT DISTINCT student.name 
       FROM student 
       INNER JOIN exam ON student.email = exam.Student_email 
       WHERE student.email = $exam_recordation[Student_email]"; 

echo "<br>query result dump: "; 
var_dump($name_query); 

的所有结果如下：

post email var dump: 
array 
    'Student_email' => string 'nuts@prof.com' (length=13) 

recordation query: SELECT Student_email FROM exam WHERE partner_id IN (SELECT partner_id FROM exam WHERE Student_email = 'nuts@prof.com') AND Student_email <> 'nuts@prof.com' 
recordation var dump: 
resource(6, mysql result) 
Name 
foiling@gorilla.com 


INNER JOIN query: SELECT DISTINCT student.name FROM student INNER JOIN exam ON student.email = exam.Student_email WHERE student.email = 
query result dump: 
boolean false 

哪里出了问题你问？在INNER JOIN中，我无法弄清楚它为什么不将来自$ exam_recordation查询的电子邮件放入它中，即使它在表格中被拾取。在更大的功能中，我会让INNER JOIN在while循环中使用记录查询来产生我期望的效果。我一直在努力解决这个问题一段时间，因为我试图修复/寻求帮助来修复整个主函数失败了，我想我会试试这个问题的INNER JOIN，因为它似乎是头撞砖墙的主要罪魁祸首。

Answer 1

$exam_recordation = mysql_query("SELECT Student_email FROM exam WHERE partner_id IN (SELECT partner_id FROM exam WHERE Student_email = $data3) AND Student_email <> $data3"); 
echo "<br>recordation query: "; 
echo "SELECT Student_email FROM exam WHERE partner_id IN (SELECT partner_id FROM exam WHERE Student_email = $data3) AND Student_email <> $data3"; 
echo "<br>recordation var dump: "; 
var_dump($exam_recordation); 
echo "<table border=='1'> 
<tr> 
<th>Name</th> 
</tr>"; 
while ($fetch_record = mysql_fetch_array($exam_recordation)) 
{ 
    echo "<tr>"; 
    echo "<td>" . $fetch_record['Student_email'] . "</td>"; 
    echo "</tr>"; 
} 

---

$name_query = mysql_query("SELECT DISTINCT student.name 
       FROM student 
       INNER JOIN exam ON student.email = exam.Student_email 
       WHERE student.email = $exam_recordation[Student_email]"); 

看到这里，你的读取与变量$ fetch_record查询，但后来你使用的是$ exam_recordation，这是唯一的MySQL查询的资源，而不是获取的数据。