Question

<?php
    include "head-main.php";
    include "conn.php";

    if(isset($_GET)){ $var = $_GET["cat"]; }
    $data = mysql_query('SELECT kampword FROM data_dict where category=$var');

   $retval = mysql_query( $data, $conn );

     if(! $retval ) {
   die('Could not get data: ' . mysql_error());
   }

   while($row = mysql_fetch_assoc($retval)) {
   echo "World :{$row['kampword']}  <br> ".
     "--------------------------------<br>";
  }

  ?>

我是编程新手，我无法追查我的代码有什么问题，你能帮助我吗？我正在尝试在我的数据库上打印一些数据

我总是得到这个错误 “无法获取数据：查询为空”

Answer 1

您正在两次调用mysql_query函数。尝试用以下代码替换你的行：

<?php
if(isset($_GET["cat"])) { 
    $var = $_GET["cat"];
    $retval = mysql_query('SELECT kampword FROM data_dict where category=$var');
}else {
    $retval = false;
}

Answer 2

$data = mysql_query("SELECT kampword FROM data_dict where category=$var");

或

$data = mysql_query('SELECT kampword FROM data_dict where category="'.$var.'"');

Answer 3

尝试

if(isset($_GET["cat"])){ $var = $_GET["cat"]; }

SQL查询错误查询为空

3 个答案: