你好我的一个php项目有问题。问题是我需要为每年的班级提供最优秀的学生以及最好的整体学生。但是我的if语句有问题;我无法发布每个学生的姓名，其名称应该显示他们当年的分数。
数据库的照片：http://imagizer.imageshack.us/a/img843/9674/7r2t.png
这是我的代码：
<body>
<form>
<?php
$username = "amar";
$password = "amar";
$hostname = "localhost";
$database = "study";
$set = 100;
$met = 0;
$mysqli = new mysqli($hostname, $username, $password, $database)
or die("Unable to connect to MySQL");
$query = "select Name, year_1, year_2, year_3, year_4, Final, Final_Grade from toppers";
$result = mysqli_query($mysqli, $query);
if (!$result) {
$message = 'Invalid query: ' . mysqli_error() . "\n";
$message .= 'Whole query: ' . $query;
die($message);
}
echo "<table border=1 cellpadding=5>";
echo "<tr><td>Student Name</td>";
echo "<td>2011</td>";
echo "<td>2012</td>";
echo "<td>2013</td>";
echo "<td>2014</td>";
echo "<td>Final Exam</td>";
echo "<td>Grade</td></tr>";
while ($row = mysqli_fetch_array($result)) {
$grader = "$_POST[result]";
$x = $row['year_1'] + $row['year_2'] + $row['year_3'] + $row['year_4'] + $row['Final'];
$grader = $x / 5;
$row[Final_Grade] = $grader;
if ($grader <= 100 and $grader >= 89) {
$grade = "A";
} elseif ($grader <= 90 and $grader >= 79) {
$grade = "B";
} elseif ($grader <= 80 and $grader >= 69) {
$grade = "C";
} elseif ($grader <= 70 and $grader >= 59) {
$grade = "D";
} else {
$grade = "F";
}
if ('$row[Final]' > $set) {
$year1 = $grade;
$year2011 = $row;
}
if ('$row[Final]' < $set) {
$year2 = $grade;
$year2012 = $row;
}
if ('$row[Final]' < $set) {
$year3 = $grade;
$year2013 = $row;
}
if ('$row[Final]' < $set) {
$year4 = $grade;
$year2014 = $row;
}
if ('$row[Final]' < $set) {
$final = $grade;
$finalscore = $row;
}
if ('$row[Final]' < $set) {
$overall = $grade;
$overall = $row;
}
echo "<tr><td>";
echo "$row[Name]";
echo "</td><td>";
echo "$row[year_1]";
echo "</td><td>";
echo "$row[year_2]";
echo "</td><td>";
echo "$row[year_3]";
echo "</td><td>";
echo "$row[year_4]";
echo "</td><td>";
echo "$row[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
}
echo "<tr><td colspan=7>Topper for 2011: </td></tr>";
echo "$year2011[Name]";
echo "</td><td>";
echo "$year2011[year_1]";
echo "</td><td>";
echo "$year2011[year_2]";
echo "</td><td>";
echo "$year2011[year_3]";
echo "</td><td>";
echo "$year2011[year_4]";
echo "</td><td>";
echo "$year2011[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
echo "<tr><td colspan=7>Topper for 2012: </td></tr>";
echo "$year2012[Name]";
echo "</td><td>";
echo "$year2012[year_1]";
echo "</td><td>";
echo "$year2012[year_2]";
echo "</td><td>";
echo "$year2012[year_3]";
echo "</td><td>";
echo "$year2012[year_4]";
echo "</td><td>";
echo "$year2012[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
echo "<tr><td colspan=7>Topper for 2013: </td></tr>";
echo "$year2013[Name]";
echo "</td><td>";
echo "$year2013[year_1]";
echo "</td><td>";
echo "$year2013[year_2]";
echo "</td><td>";
echo "$year2013[year_3]";
echo "</td><td>";
echo "$year2013[year_4]";
echo "</td><td>";
echo "$year2013[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
echo "<tr><td colspan=7>Topper for 2014: </td></tr>";
echo "$finalscore[Name]";
echo "</td><td>";
echo "$finalscore[year_1]";
echo "</td><td>";
echo "$finalscore[year_2]";
echo "</td><td>";
echo "$finalscore[year_3]";
echo "</td><td>";
echo "$finalscore[year_4]";
echo "</td><td>";
echo "$finalscore[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
echo "<tr><td colspan=7>Topper overall: </td></tr>";
echo "$overall[Name]";
echo "</td><td>";
echo "$overall[year_1]";
echo "</td><td>";
echo "$overall[year_2]";
echo "</td><td>";
echo "$overall[year_3]";
echo "</td><td>";
echo "$overall[year_4]";
echo "</td><td>";
echo "$overall[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
echo "</table>";
答案 0 :(得分：2)
PHP中单引号的所有内容都被解释为字符串。当您执行'$row[Final]' PHP时，将其解释为“美元符号，左括号，单词'最终'，关闭括号。”
为了让PHP解释您所说的变量的引用，您必须仅将您的索引作为字符串引用，而将其余部分引用到引号之外。
$row["Final"];告诉PHP，“检查变量$row并查看存储在字符串Final所代表的索引的内容。”
答案 1 :(得分：0)
看起来您需要为之后要显示的每个组（即每年最高的组）存储最高的结果，而不是仅在$ set中存储一个最高的商店。
不是100％肯定你想要什么，而是给你一个这样的想法： -
<body>
<form>
<?php
$username = "amar";
$password = "amar";
$hostname = "localhost";
$database = "study";
$set = array('2011'=>0, '2012'=>0, '2013'=>0, '2014'=>0, 'final'=>0, 'Final_Grade'=>0);
$mysqli = new mysqli($hostname, $username, $password, $database)
or die("Unable to connect to MySQL");
$query = "select Name, year_1, year_2, year_3, year_4, Final, Final_Grade from toppers";
$result = mysqli_query($mysqli, $query);
if (!$result) {
$message = 'Invalid query: ' . mysqli_error() . "\n";
$message .= 'Whole query: ' . $query;
die($message);
}
echo "<table border=1 cellpadding=5>";
echo "<tr><td>Student Name</td>";
echo "<td>2011</td>";
echo "<td>2012</td>";
echo "<td>2013</td>";
echo "<td>2014</td>";
echo "<td>Final Exam</td>";
echo "<td>Grade</td></tr>";
while ($row = mysqli_fetch_array($result))
{
$grader = $_POST['result'];
$x = $row['year_1'] + $row['year_2'] + $row['year_3'] + $row['year_4'] + $row['Final'];
$grader = $x / 5;
$row['Final_Grade'] = $grader;
switch (true)
{
case ($grader <= 100 and $grader >= 89) :
$grade = "A";
break;
case ($grader <= 90 and $grader >= 79) :
$grade = "B";
break;
case ($grader <= 80 and $grader >= 69) :
$grade = "C";
break;
case ($grader <= 70 and $grader >= 59) :
$grade = "D";
break;
default :
$grade = "F";
break;
}
if ($row['Final'] > $set['2011'])
{
$year2011 = $row;
$set['2011'] = $row['Final'];
}
if ($row['Final'] < $set['2012'])
{
$year2011 = $row;
$set['2011'] = $row['Final'];
}
if ($row['Final'] < $set['2013'])
{
$year2011 = $row;
$set['2011'] = $row['Final'];
}
if ($row['Final'] < $set['2014'])
{
$year2011 = $row;
$set['2011'] = $row['Final'];
}
if ($row['Final'] < $set['final'])
{
$finalscore = $row;
$set['final'] = $row['Final'];
}
if ($row['Final_Grade'] < $set['Final_Grade'])
{
$overall = $row;
$set['Final_Grade'] = $row['Final_Grade'];
}
echo "<tr><td>";
echo "$row[Name]";
echo "</td><td>";
echo "$row[year_1]";
echo "</td><td>";
echo "$row[year_2]";
echo "</td><td>";
echo "$row[year_3]";
echo "</td><td>";
echo "$row[year_4]";
echo "</td><td>";
echo "$row[Final]";
echo "</td><td>";
echo "$grade";
echo "</td></tr>";
}
echo "<tr><td colspan=7>Topper for 2011: </td></tr>";
echo "<tr><td>".implode("</td><td>", $year2011)."</td></tr>";
echo "<tr><td colspan=7>Topper for 2012: </td></tr>";
echo "<tr><td>".implode("</td><td>", $year2012)."</td></tr>";
echo "<tr><td colspan=7>Topper for 2013: </td></tr>";
echo "<tr><td>".implode("</td><td>", $year2013)."</td></tr>";
echo "<tr><td colspan=7>Topper for 2014: </td></tr>";
echo "<tr><td>".implode("</td><td>", $year2014)."</td></tr>";
echo "<tr><td colspan=7>Topper overall: </td></tr>";
echo "<tr><td>".implode("</td><td>", $overall)."</td></tr>";
echo "</table>";