如何减少数据库表中的值 [英] How to decrease value from a database table

问题描述

我不确定我的代码是对还是错



我尝试了什么：



HTML

< section id =registerclass =register-section> 
 
< div class =container> 
< div class =row> 
< div class =col-sm-12> 
< div class =section-title> 
< h2>在这里注册课程!! < / H2> 
< br> 
< form action =index2.phpmethod =post> 
< h3>名称：< / h3> 
< input name =Nametype =textid =Nameplaceholder =Namerequired /> 
< br>< br> 
< h3>课程申请：< / h3> 
< input name =Course_Nametype =textid =Course_Name占位符=课程申请必需/> 
< br>< br> 
< h3>电子邮件：< / h3> 
< input name =Emailtype =emailid =Emailplaceholder =Emailrequired /> 
< br>< br> 
 
< h3>联系方式：< / h3> 
< input name =Contacttype =textid =Contactplaceholder =Contactrequired /> 
< br>< br> 
< h3>注册日期：< / h3> 
< input name =Register_Datetype =dateid =Register_Date占位符=注册日期需要/> 
< / div> 
< / div> 
< / div> 
< div style =text-align：center; padding-top：30px;> 
< input class =btntype =submitname =saveid =savevalue =Save/> 

SQL / PHP

<？php 
 require_once（'Database.php'）; 
 
 
 // $ Name = mysql_real_escape_string（$ _REQUEST [Name]）; 
 $ Course_Name = mysql_real_escape_string（$ _REQUEST [Course_Name]）; 
 // $ Email = mysql_real_escape_string（$ _REQUEST [Email]）; 
 // $ Contact = mysql_real_escape_string（$ _REQUEST [Contact]）; 
 // $ Register_Date = mysql_real_escape_string（$ _REQUEST [Register_Date]）; 
 $ Avail_Seats = mysql_real_escape_string（$ _REQUEST [Avail_Seats]）; 
 
 $ sql =SELECT * FROM tblcourse WHERE Course_Name ='。 $ Course_Name。 ; 
 
 $ result = mysql_query（$ sql，$ dbconn）; 
 if（$ result）{
 $ sql =（UPDATE tblcourse 
 SET Avail_Seats = IF（Avail_Seats> 0，field  -  1,0）
 WHERE Course_Name = $ Course_Name ）; 
} 
 
 
 
 
？> 

解决方案

< blockquote> Name = mysql_real_escape_string（

_REQUEST [Name]）;

Course_Name = mysql_real_escape_string（

im not sure if im code is right or wrong

What I have tried:

HTML

<section id="register" class="register-section">
       
       	  <div class="container">
            <div class="row">
                <div class="col-sm-12">
                    <div class="section-title">
                        <h2> Register Course Here!! </h2>
						<br>
				<form action="index2.php" method="post">
						<h3> Name: </h3>
						<input name="Name" type="text" id="Name" placeholder="Name" required />
						<br><br>
						<h3> Course Applying: </h3>
						<input name="Course_Name" type="text" id="Course_Name" placeholder="Course Apply" required />
						<br><br>
						<h3> Email : </h3>
						<input name="Email" type="email" id="Email" placeholder="Email" required />
						<br><br>
						
						<h3> Contact : </h3>
						<input name="Contact" type="text" id="Contact" placeholder="Contact" required />
					<br><br>
					<h3> Registitration Date : </h3>
						<input name="Register_Date" type="date" id="Register_Date" placeholder="Registitration date" required />
	       </div>
                </div>
            </div>				
				<div style="text-align: center; padding-top: 30px;">
					<input class="btn" type="submit" name="save" id="save" value="Save" />

SQL/PHP

<?php 
	require_once ('Database.php'); 
	

	//$Name = mysql_real_escape_string ($_REQUEST["Name"]);
	$Course_Name = mysql_real_escape_string ($_REQUEST["Course_Name"]);
	//$Email = mysql_real_escape_string ($_REQUEST["Email"]);
	//$Contact = mysql_real_escape_string ($_REQUEST["Contact"]);
	//$Register_Date = mysql_real_escape_string ($_REQUEST["Register_Date"]);
	$Avail_Seats = mysql_real_escape_string ($_REQUEST["Avail_Seats"]);
	
	$sql = "SELECT * FROM tblcourse WHERE Course_Name = '" . $Course_Name . "'";

	$result = mysql_query ($sql, $dbconn);
	if ($result)  {
$sql =("UPDATE  tblcourse
SET     Avail_Seats = IF(Avail_Seats > 0, field - 1, 0)
WHERE  Course_Name = $Course_Name");
	}	

	


?>

解决方案

Name = mysql_real_escape_string (

_REQUEST["Name"]);

Course_Name = mysql_real_escape_string (

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