php - 为什么 PHP 的下拉列表中 mysql 数据库的值没有设置为 "selected"

Question

这并不反射(reflect)数据库中的数据。我不知道为什么，但除此之外其他下拉菜单都可以正常工作。对于有效的 WHERE 子句来说，该条件有 2 个条件。不起作用的是根据数据库中保存的数据选择数据。再说一遍，我还有其他 2 个下拉菜单，这些下拉菜单正在运行。

<font> Course/Year/Section</font>

<?php
$sqlA = "SELECT Course FROM tblcys";
$resultA = mysql_query($sqlA);

echo "<select name='Course' required>";
echo "<option value=''>Select Course</option>";
while ($rw = mysql_fetch_array($resultA)) { ?>
    <option value="<?php echo $rw['Course']; ?>"<?php if($rw['Course']==$Course) echo 'selected="selected"'; ?>><?php echo $rw['Course']; ?></option>
    <?php
}
echo "</select>" ?>

<?php
$sqlB = "SELECT Year FROM tblcys WHERE Course ='". $Course. "' ORDER BY Year ASC";
$resultB = mysql_query($sqlB);

echo "<select name='Year' required>";
echo "<option value=''>Select Year</option>";
while ($rw1 = mysql_fetch_array($resultB)) { ?>
    <option value="<?php echo $rw1['Year']; ?>"<?php if($rw1['Year']==$Year) echo 'selected="selected"'; ?>><?php echo $rw1['Year']; ?></option>
    <?php
}

这个不起作用

<?php
$sqlC = "SELECT Section FROM tblcys WHERE tblcys.Course ='". $Course. "' AND tblcys.Year ='". $Year. "' ORDER BY Section ASC";
$resultC = mysql_query($sqlC);

echo "<select name='Section' required>";
echo "<option value=''>Select Section</option>";
while ($rw2 = mysql_fetch_array($resultC)) { ?>
    <option value="<?php echo $rw2['Section']; ?>"<?php if($rw2['Section']==$Section) echo 'selected="selected"'; ?>><?php echo $rw2['Section']; ?></option>
    <?php
}
echo "</select>" ?>

这些是有关正在传递的变量的其他详细信息。

$result2=mysql_query("Select * From tblrecord where studID='$ID'");
while($row=mysql_fetch_array($result2))
{

$RFIDNo=$row['RFIDNo'];
$studID=$row['studID'];
$lname=$row['lname'];
$fname=$row['fname'];
$mi=$row['mi'];
$Course=$row['Course'];
$Year=$row['Year'];
$Section=$row['Section'];
$Section=$row['Status'];
}

Answer 1

尝试从语句中删除表引用:

$sqlC = "SELECT Section FROM tblcys WHERE tblcys.Course ='". $Course. "' AND tblcys.Year ='". $Year. "' ORDER BY Section ASC";

至

$sqlC = "SELECT Section FROM tblcys WHERE Course ='". $Course. "' AND Year ='". $Year. "' ORDER BY Section ASC";