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POPHP - echo missing entries
 

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    <p>I have a problem.</p> <p>I have three tables <strong>class_tbl,subject_tbl, and *student_tbl</strong>. class_tbl has 3 columns *"class_id, subject_id, and student_id".* while subject_tbl has 4 columns *"subject_id,subject_name,subject_yr,subject_sem"* and lastly *student_tbl has 2 columns "student_id and student_name".*</p> <p>class_tbl has these rows:</p> <pre><code>**[class_id || subject_id || student_id]** || 1001 || 2002 || 3003 || 1002 || 2003 || 3003 || 1003 || 2004 || 3003 </code></pre> <p>subject_tbl has 5 rows:</p> <pre><code>**[subject_id || subject_name || subject_yr || subject_sem]** || 2002 || Math || 2010 || 1st || 2003 || Science || 2010 || 1st || 2004 || History || 2010 || 1st || 2005 || PE || 2010 || 1st || 2006 || Social Studies || 2010 || 1st </code></pre> <p>student_tbl has 1 row: depending on the number of students actually</p> <pre><code>**[student_id || student_name]** || 3003 || John Parker </code></pre> <p>The goal here is that the query will echo the last 2 subjects which is PE and Social Studies so that I can insert them to class_tbl. The echo is telling me that I dont have 2 entries for the 2 subject during that semester and school year. The query will not echo the subjects which are already in the entries of class_tbl which are Math,Science, and History. How do I query and echo the missing subjects of that semester and year? I really cant come up with any idea. Help tnx!</p> <p>The code here displays all subjects of that school_yr and semester.</p> <pre><code> if (isset ($db1)&amp;&amp;$db1!=""){ } &lt;?php $student_id = $_POST['student_id']; $sem = $_POST['sem']; $yr = $_POST['yr']; $list = mysql_query("SELECT * FROM class_tbl LEFT JOIN subject_tbl ON class_tbl.subject_id = subject_tbl.subject ID WHERE student_id = '$student_id' OR subject_sem = '$sem' OR subject_yr = '$yr' ORDER BY subject_id asc"); while($row_list=mysql_fetch_assoc($list)) { echo $row_list['subject_id']; if($row_list['subject_id']==$db1){echo "selected"; } echo $row_list['subject_name']; } </code></pre> <p>The example output would be:</p> <p>You have 2 missing subjects "PE and Social Studies." </p>
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    1. COplease structure it a little more human-readable (for example make things bold or italic)
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    2. COif you used http://sqlfiddle.com/, then helping you would be easy
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