Php 请问，在我将顺序转换为desc后，为什么仍然有错误？下面是错误消息“error！您的SQL语法有错误；请查看与您的MySQL服务器版本对应的手册，以了解第3行附近的'T.TechName ASC，L.Time DESC'使用的正确语法”啊，对不起，我相信您

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请问，在我将顺序转换为desc后，为什么仍然有错误？下面是错误消息“error！您的SQL语法有错误；请查看与您的MySQL服务器版本对应的手册，以了解第3行附近的'T.TechName ASC，L.Time DESC'使用的正确语法”啊，对不起，我相信您不能同时使用ASC和DESC。只需使用DESC或ASC在最后或您的查询，这是可以这样做，因为当我改变它像上面给出的代码，它现在没有问题（至少现在工作）哦，我明白了，因为我只是按照这样的方式写C++，所以犯这种粗心的错误，对不起。切换语言时的差异；）请问，在我将顺序转换为desc后，为什么仍然有错误？下面是错误消息“error！您的SQL语法有错误；请查看与您的MySQL服务器版本对应的手册，以了解第3行附近的'T.TechName ASC，L.Time DESC'使用的正确语法”啊，对不起，我相信您不能同时使用ASC和DESC。只需在末尾使用DESC或ASC，或者您的查询我认为这样做是可以的，因为当我像上面给出的代码那样更改它时，它现在就没有问题了（至少它现在可以工作了）

$query = "SELECT * 
    FROM Tech AS T, Client AS C, Site AS S, Log AS L 
    WHERE T.TechID=L.TechID, C.ClientID=L.ClientID, S.SiteID=L.SiteID";
if($sort=="Tech")
   $query += "ORDER BY T.TechName ASC, L.Time DSC";
else if($sort=="Client")
   $query += "ORDER BY C.ClientName ASC, L.Time DSC";
$result = mysql_query($query) or die('Error! ' . mysql_error());; 
print "Real-Time check in/check out<br>";
print "<table><th><td>Tech</td><td>Client</td><td>Site</td>";
print "<td>Date and Time</td><td>Type</td></th>";
while($row = mysql_fetch_array($result)){
print "<tr><td>".$row['T.TechName']."</td>";
print "<td>".$row['C.ClientName']."</td>";
print "<td>".$row['S.SiteName']."</td>";
print "<td>".$row['L.Time']."</td>";
print "<td>".$row['L.Type']."</td></tr>";
}
print "</table>";

SELECT * 
FROM Tech AS T, Client AS C, Site AS S, Log AS L 
WHERE T.TechID=L.TechID AND C.ClientID=L.ClientID AND S.SiteID=L.SiteID

SELECT * 
FROM Tech AS T
JOIN Client AS C on T.TechID=L.TechID
JOIN Site AS S on C.ClientID=L.ClientID
JOIN Log AS L on S.SiteID=L.SiteID

if (...) {
} else {
    if (...) {
    }
}

# Future improvement: abstract each section into methods that are part of separate layers

# Database access
$statement = 'SELECT T.TechName, C.ClientName, S.SiteName, L.Time, L.Type 
    FROM Log AS L
      JOIN Tech AS T ON T.TechID=L.TechID
      JOIN Client AS C ON C.ClientID=L.ClientID
      JOIN Site AS S ON S.SiteID=L.SiteID';

if ($sort === 'Tech') {
   $query .= ' ORDER BY T.TechName ASC, L.Time DESC';
} elseif ($sort === 'Client') {
   $query .= ' ORDER BY C.ClientName ASC, L.Time DESC';
}

try {
    $data = $db->query($statement);
} catch (PDOException $exc) {
    $data = array();
    # handle error appropriately: inform user that there was an internal error. Log the actual error and possibly notify the dev team.
    ...
}

# Output/User interface
$fields = array('TechName' => 'Tech', 'ClientName' => 'Client', 'SiteName' => 'Site', 'Time' => 'Date and Time', 'Type' => 'Type');
if ($data) {
    ?>
    <h3>Real-Time check in/check out</h3>
    <table>
      <thead>
        <tr><th><?php echo implode('</th><th>', $fields) ?></th></tr>
      </thead>
      <tbody>
        <?php foreach ($data as $row) { ?>
          <tr>
            <?php foreach ($fields as $field => $label) { ?>
              <td><?php echo $row[$field] ?></td>
            <?php } ?>
          </tr>
        <?php } ?>
      </tbody>
    </table>
    <?php
}

$query = "SELECT * 
    FROM Tech AS T, Client AS C, Site AS S, Log AS L 
    WHERE T.TechID=L.TechID AND C.ClientID=L.ClientID AND S.SiteID=L.SiteID";
if($sort=="Tech")
   $query .= " ORDER BY T.TechName ASC, L.Time DESC";
else if($sort=="Client")
   $query .= " ORDER BY C.ClientName ASC, L.Time DESC";

L.SiteIDORDERBY

L.SiteID ORDER BY