duanpuluan0480
2017-11-05 16:44
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MySQL中的WHERE子句用于选择所有

I have a script in PHP, which selects data from a Mysql Database using Select & Where clause.

$lrn= "PU2017LN11K";
$stmt = $user_home->runQuery('SELECT * FROM mcq WHERE LRN = :crn ORDER BY LRN,Sr ASC ');
$stmt->bindParam(':crn',$lrn);
$stmt->execute();

Now how to script the code so that it selects from all the LRN, using WHERE LRN = :crn.

I tried:

$lrn= "*";
$stmt = $user_home->runQuery('SELECT * FROM mcq WHERE LRN = :crn ORDER BY LRN,Sr ASC ');
$stmt->bindParam(':crn',$lrn);
$stmt->execute();

But it didn't show any results!

It's easy to skip the WHERE clause if I want to show all results, but the value of $lrn will be defined by the $_GET method.

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我在 PHP 中有一个脚本，它从 Mysql <中选择数据 / code>数据库使用选择＆amp; Where 子句。 

  $ lrn =“PU2017LN11K”; 
 $ stmt = $ user_home-＆gt; runQuery（'SELECT * FROM mcq WHERE LRN  =：crn ORDER BY LRN，Sr ASC'）; 
 $ stmt-＆gt; bindParam（'：crn'，$ lrn）; 
 $ stmt-＆gt; execute（）; 
   
 
 
现在如何编写代码脚本，以便使用 WHERE LRN =：crn 从所有 LRN 中进行选择。 
  
 
我试过了： 
 
 
  $ lrn =“*”; 
 $ stmt = $ user_home-＆gt; runQuery（'SELECT * FROM mcq WHERE LRN =：  crn ORDER BY LRN，Sr ASC'）; 
 $ stmt-＆gt; bindParam（'：crn'，$ lrn）; 
 $ stmt-＆gt; execute（）; 
   \  n 
 
但它没有显示任何结果！ 
 
 
如果我想显示所有结果，可以轻松跳过 WHERE 子句，但是\   $ _ Gn 方法将定义 $ lrn 的值。
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3条回答 默认 最新

  • dpchen2004 2017-11-05 16:51
    最佳回答

    The normal way of handling this would be:

    $lrn= "*";
$stmt = $user_home->runQuery('SELECT * FROM mcq WHERE LRN = :crn OR :crn = \'*\' ORDER BY LRN, Sr ASC ');

    Alternatively, you could use LIKE:

    $lrn = "%";
$stmt = $user_home->runQuery('SELECT * FROM mcq WHERE LRN LIKE :crn ORDER BY LRN, Sr ASC ');
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