Question

我试图找出编写查询的适当方法，该查询将根据是否存在一个或两个变量来显示结果。虽然我正在学习，但我对PHP仍然很陌生，虽然很慢。

我的当前代码仅接受一个搜索条件的变量，如下所示。如你所见，我只有一个_POST变量，我收到$ reg

我想做的是接收第二个变量

$toest=$_POST['toestelID'];

如果只有$reg包含值{且$toest为Null / Empty），我希望它能够查询WHERE语句

WHERE vg.luchtvaartmaatschappijID= '$reg'

如果$ reg和$ toest都包含值，那么它将是在哪里vg.luchtvaartmaatschappijID =＆＃39; $ reg＆＃39; AND vg.toestelID =＆＃39; $ toest＆＃39;

我知道这可以通过IF / Else类型声明来完成，我只是不知道如何对此进行编程。

原始代码：

<?php
$reg=$_POST['luchtvaartmaatschappijID'];
if(isset($_POST['submit'])){
if(isset($_GET['go'])){

$reg=$_POST['luchtvaartmaatschappijID'];
$color1 = "#C2DFFF";  
$color2 = "#FFFFFF"; 
$row_count = 0;
//connect  to the database
$db=mysql_connect  ("localhost", "someusername",  "somepassword") or die ('I cannot connect to 
the database  because: ' . mysql_error());
//-select  the database to use
$mydb=mysql_select_db("somedatabase");
//-query  the database table
$sql="SELECT vg.*, lvm.luchtvaartmaatschappij AS lvmnaam, lvm.luchtvaartmaatschappijID as lvmid, 
t.toestel

FROM tbl_vliegtuiggegevens vg

INNER JOIN tbl_luchtvaartmaatschappij lvm
ON vg.lvmID = lvm.luchtvaartmaatschappijID

INNER JOIN tbl_toestel t
ON vg.toestelID = t.toestelID

WHERE vg.luchtvaartmaatschappijID= '$reg'
ORDER BY lvm.luchtvaartmaatschappij ASC, t.toestel ASC, vg.inschrijvingnmr ASC";
//-run  the query against the mysql query function

$result=mysql_query($sql);


echo "zoekresultaten:<br>
<table border='0' cellspacing='0'>
<tr>
<th width='100' valign='top'><div align='left'>cn</div></th>
 <th width='150' valign='top'><div align='left'>reg</div></th>
<th width='300' valign='top'><div align='left'>Luchtvaartmaatschappij</div></th>
<th width='330' valign='top'><div align='left'>Toestel</div></th>
</tr>
<tr>
<th height='1' colspan='4' valign='top' bgcolor='#333333'></th>
</tr>";
//-create  while loop and loop through result set
while($row=mysql_fetch_array($result)){
       $row_color = ($row_count % 2) ? $color1 : $color2;
      $reg=$row['inschrijvingnmr'];
      $toestel=$row['toestel'];
       $cnid=$row['cn'];
       $lvmid=$row['lvmid'];
       $lvmnaam=$row['lvmnaam'];
      $ID=$row['vliegtuiggegevenID'];
//-display the result of the array

echo "<tr>";
echo "<td bgcolor='$row_color'>".$cnid."</td>";
echo "<td bgcolor='$row_color'><a target='_blank' 
href=\"../vliegtuiggegevens/vliegtuiggegevens_form.php?id=$reg&cid=$cnid&lvid=$lvmid\">"   .$reg  
. "</a></td>";
echo "<td bgcolor='$row_color'>" . $lvmnaam . "</td>";
echo "<td bgcolor='$row_color'>" . $toestel . "</td>";
echo "</tr>";
// Add 1 to the row count 
$row_count++; 

}
echo "</table>";

}

if( mysql_num_rows($result) == 0 )
{
include('../vliegtuiggegevens/voegvliegtuiggegevenstoe_form.php');
} 

}
?>

Answer 1

首先我强烈建议使用PDO，不仅更安全（没有sql注入）。当你掌握它时，它可以更容易使用，并提供更多关于如何处理结果数据的方法。不推荐使用mysql函数库。所以你应该使用PDO或mysqli。

要回答你的问题，我想建立一个这种情况的条件数组。例如，

 $PDO = new Pdo('mysql:host=localhost;database', 'user', 'password');
 //enable pdo error reporting, now you don't need all those die( 'bla' ) stuff.
 $PDO->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

 //create a stub of your query
 $sql = 'SELECT * FROM some_table WHERE';
 $where = array();
 $params = array();

 if( isset($_POST['something'] ) ){
     $where[] = 'something = :something'; // using pdo placeholder
     $params[':something'] = $_POST['something'];
 }

 if( isset($_POST['otherthing'] ) ){
     $where[] = 'otherthing = :otherthing'; // using pdo placeholder
     $params[':otherthing '] = $_POST['otherthing'];
 }

  //if you need a default value simply count your wheres
  // if not just use the part in the else chunk
  if( empty( $where ) ){
      $sql .= ' id = 0'; //no results on empty conditions etc... 
  }else{
      //now that you have some stuff
      $sql .= ' '.implode(' AND ', $where); //collapse it
  }

  // pdo can be trickier to see what your query actually is
  // so you can do something like this to check it out. but you'll have to do the quotes etc..
  //echo str_replace( array_keys( $params ), $params, $sql );

  //prepare the query 
  $stmt = $PDO->prepare( $sql );
  //execute it
  $stmt->execute( $params );
  //fetch the results
  $res = $stmt->fetchAll(PDO::FETCH_ASSOC);

这应该会给你一些你需要的东西。

供参考

http://php.net/manual/en/book.pdo.php

（参见以下链接中的示例＃2）

http://php.net/manual/en/pdostatement.execute.php

Answer 2

是的，你做对了 - 你需要的是一些if和else语句。这是一个应该有用的代码片段：

$toest=$_POST['toestelID'];
$reg=$_POST['reg'];
$where_stmt="";
if((isset($reg) && !empty($reg)) && (!isset($toest) || empty($toest)))
{
    $where_stmt="WHERE vg.luchtvaartmaatschappijID='".$reg."'";
}
elseif((isset($toest) && !empty($toest)) && (!isset($reg) || empty($reg)))
{
    $where_stmt="WHERE vg.toestelID='".$toest."'";
}
elseif(isset($reg) && !empty($reg) && isset($toest) && !empty($toest))
{
    $where_stmt="WHERE vg.luchtvaartmaatschappijID='".$reg."' and vg.toestelID='".$toest."'";
}
else
{
    //where statement should be excluded as no filters are available
}
$sql="SELECT vg.*, lvm.luchtvaartmaatschappij AS lvmnaam, lvm.luchtvaartmaatschappijID as lvmid, 
t.toestel FROM tbl_vliegtuiggegevens vg INNER JOIN tbl_luchtvaartmaatschappij lvm ON vg.lvmID = lvm.luchtvaartmaatschappijID INNER JOIN tbl_toestel t ON vg.toestelID = t.toestelID $where_stmt ORDER BY lvm.luchtvaartmaatschappij ASC, t.toestel ASC, vg.inschrijvingnmr ASC";

如果变量empty / null显示结果，如果变量not null则显示其他结果

2 个答案: