单条件和多条件查询

首先在数据库中，做这样一张汽车表：

然后写代码，在页面中导出这张表

再在上面加个文本框还有查询按钮

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<h1>汽车查询</h1>
<?php
$db = new MySQLi("localhost","root","726","shuang" );
$tj = " 1=1";    //条件默认恒成立
$name = "";
if(!empty($_POST["name"]))
{
    $name = $_POST["name"];
    $tj = " name like '%{$name}%'";
}


?>
<form action="carchaxun.php" method="post">
<div>请输入名称：
<input type="text" name="name" />
<input type="submit" value="查询" />
</div>
<br />
<table width="100%" border="1" cellpadding="0" cellspacing="0">
<tr>
<td>代号</td>
<td>名称</td>
<td>系列</td>
<td>时间</td>
<td>油耗</td>
<td>功率</td>
</tr>
<?php
  
  $sql = "select * from car where {$tj}";
  echo $sql;
  $relsult = $db->query($sql);
  $attr=$relsult->fetch_all();
  foreach($attr as $v)
  {
                         //"<span style='color:red'>{$name}</span>"  这个方式也可以，让字体变红
     $str=str_replace($name,"<mark>{$name}</mark>",$v[1]);        mark可以用于标记
      echo "<tr>
    <td>{$v[0]}</td>
    <td>{$str}</td>
    <td>{$v[2]}</td>
    <td>{$v[3]}</td>
    <td>{$v[4]}</td>
    <td>{$v[5]}</td>
        </tr>";
      
      }
?>
</table>
</body>
</html>

运行后：

输入关键字“奥迪”

单条件查询就做好了

下面再来新建一个页面，做多条件查询

先复制单条件查询页面的代码，在它的条件上增加，改变

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<h1>汽车查询</h1>
<?php
$db = new MySQLi("localhost","root","726","shuang" );
$tj1 = "1=1";
$tj2 = "1=1";
$name = "";
if(!empty($_POST["name"]))
{
    $name = $_POST["name"];
    $tj1 = "name like '%{$name}%'";
}
if(!empty($_POST["brand"]))
{
    $brand = $_POST["brand"];
    $tj2 = " brand = '{$brand}'";
}
?>
<form action="carduotiaojian.php" method="post">
<div>请输入名称：
<input type="text" name="name" />
请输入系列代号：
<input type="text" name="brand" />
<input type="submit" value="查询" />
</div>
<br />
<table width="100%" border="1" cellpadding="0" cellspacing="0">
<tr>
<td>代号</td>
<td>名称</td>
<td>系列</td>
<td>时间</td>
<td>油耗</td>
<td>功率</td>
</tr>
<?php
  
  $sql = "select * from car where {$tj1} and {$tj2}";
  echo $sql;
  $relsult = $db->query($sql);
  $attr=$relsult->fetch_all();
  
  if(count ($attr)>0)    //判断有没有输出数据
  {
  
  foreach($attr as $v)
  {
                         //"<span style='color:red'>{$name}</span>"  这个方式也可以，让字体变红
     $str=str_replace($name,"<mark>{$name}</mark>",$v[1]);
      echo "<tr>
    <td>{$v[0]}</td>
    <td>{$str}</td>
    <td>{$v[2]}</td>
    <td>{$v[3]}</td>
    <td>{$v[4]}</td>
    <td>{$v[5]}</td>
        </tr>";
      
      }
  }
  else
  {
      echo  "<script> alert ('没有查到数据');</script>";
  }
?>
</table>
</body>
</html>