如何防止动态下拉列表中的重复 [英] how to prevent duplicates in dynamic drop down list

问题描述

下面是带有动态下拉列表的代码FORM

 <？php  
 $ select_query =  从书籍中选择类别; 
  $ select_query_run  = mysql_query（$ select_query）; 
 $ select_query_array = mysql_fetch_array（$ select_query_run）; 
  $ cat  = $ select_query_array ['  category ]; 
  echo   < select name ='类别>中; 
  while （$ select_query_array = mysql_fetch_array（$ select_query_run））
 {
  echo   < option value =''> .htmlspecialchars（$ select_query_array [  category]）。 < /选项>中; 
} 
 
  echo   < /选择> 中; 
 ？>  

类别专栏我有不同类型的书籍类别，如小说，期刊，非小说等。为了显示这一点，我创建了动态下拉列表，它将从数据库表中获取类别列下的所有值。我的问题是我无法阻止重复。例如：类别有四个小说和两个期刊。我的下拉列表也显示了四个小说和两个期刊。我不想像这样展示任何我希望只展示小说，期刊，非小说的价值观。

我想要防止重复是下拉列表。请任何人帮助我....

解决方案

select_query = 从书籍中选择类别;

select_query_run = mysql_query（

select_query）;

below is the code FORM with dynamic drop down list

<?php
$select_query=          "Select category from books";
$select_query_run =     mysql_query($select_query);
$select_query_array=   mysql_fetch_array($select_query_run) ;
 $cat = $select_query_array['category'];
echo "<select name='category'>";
while ($select_query_array=   mysql_fetch_array($select_query_run) )
{
  echo "<option value='' >".htmlspecialchars($select_query_array["category"])."</option>";
}

echo "</select>";
?>

under category column i have different types of books categories like "fiction,journal,non-fiction, etc". to show this I created dynamic drop down list which will fetch all values under category column from database table. my problem is I am unable to prevent duplication for this. ex: category have four fiction and two journal. my drop down list is also showing four fiction and two journals. I don't want to show like this way for any values I want to show only fiction,journal,non-fiction.
simply I want to prevent duplication is drop down list. please anyone help me....

解决方案

select_query= "Select category from books";

select_query_run = mysql_query(

select_query);

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