How to implement conditional query in php
How to implement conditional query in php: first call the previously encapsulated class; then use keyword fuzzy query; then create a form, submit the data to the current page, extract the keyword query; and finally use PHP code Traverse the elements in the table and turn the keywords into red.
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1. Single condition Query is a query with only one condition:
1. First call the previously encapsulated class, and then use keywords to fuzzy query:
<?php //单查询
require "DBDA.class.php";//调取封装类
$db=new DBDA;
$Sname="";//创建变量，为了后面可以让Sname在表单中显示
$sql="select * from t_student";
if(!empty($_POST["Sname"]))//确定是否存在数据
{
$Sname=$_POST["Sname"];
$sql="select * from t_student where Sname like '%{$Sname}%' ";//模糊查询
}
?>2. Create a form, submit the data to the current page, and extract the keyword query:
<form action="chaxun.php" method="post"><!--因为查询数据在当前页面，所以提交到当前页面-->
<div>姓名：<input type="text" name="Sname" value="<?php echo $Sname ?>" />
<input type="submit" value="查询" /></div>
</form><br />
<table width="100% " border="1" cellpadding="0" cellspacing="0">
<tr>
<td>姓名</td>
<td>性别</td>
<td>班级</td>
</tr>3. Traverse the elements in the table and turn the keywords into red:
<?php
$arr=$db->query($sql);
foreach($arr as $v)
{
$str = str_replace($Sname,"<span style='color:red'>{$Sname}</span>",$v[1]);//用span标签使关键字变为红色，
echo "<tr>
<td>{$str}</td>
<td>{$v[2]}</td>
<td>{$v[4]}</td>
</tr>";
}
?>Final result:
## 2. Multi-condition query:
1. First make a form and create a table to display the table:
<table width="100%" border="1" cellpadding="0" cellspacing="0">
<tr>
<td>代号</td>
<td>名称</td>
<td>系列</td>
<td>上市时间</td>
<td>价格</td>
</tr>
</table>2. Call the encapsulation class, create corresponding conditions, and check whether the data is empty :
<?php
require "DBDA.class.php";
$db=new DBDA();//1.如果没有提交数据，显示所有//2.如果有提交数据，根据关键字查询显示$name="";
$tj1=" 1=1 "; //第一个条件，对应名称，要用空格隔开$tj2=" 1=1 ";//第二个条件，对应系列，要用空格隔开if(!empty($_POST["name"]))
{
$name = $_POST["name"];
$tj1 = " name like '%{$name}%' ";
}if(!empty($_POST["brand"]))
{
$brand = $_POST["brand"];
$tj2 = " brand = '{$brand}' ";
}//总条件$tj=" {$tj1}and{$tj2} ";
$sql="select * from car where".$tj;?>3. Use PHP code to traverse the database table and turn the keywords into red (php should be embedded in the table):
<?php
$arr = $db->query($sql);foreach($arr as $v)
{
$str = str_replace($name,"<span style='color:red'>{$name}</span>",$v[1]);
echo "<tr>
<td>{$v[0]}</td>
<td>{$str}</td>
<td>{$v[2]}</td>
<td>{$v[3]}</td>
<td>{$v[7]}</td>
</tr>";}?>The final result is:
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