javascript 检查数据库中是否存在电子邮件文本框值
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Check whether the email textbox value exists in database
提问by saru
I want to check the value in text box is present in database and clear the box if the value exists in the database without refreshing the whole page.
我想检查文本框中的值是否存在于数据库中，如果该值存在于数据库中而不刷新整个页面，则清除该框。
HTML:
HTML：
<p>Email<input type="text" name="email" id="email" size=18 maxlength=50 required></p>
Query:
询问：
$echeck="select email from register where email='$email'";
$echk=mysql_query($echeck);
$ecount=mysql_num_rows($echk);
if($ecount!=0)
{
echo ("<SCRIPT LANGUAGE='JavaScript'>
var asign=document.getElementById(email); //now show null value
asign.value="";
</SCRIPT>");
}
If I use alert it will refresh the page.
如果我使用警报，它将刷新页面。
window.alert('Email Id already exist');
回答by Suchit kumar
try to implement something like this:
尝试实现这样的事情：
<script type="text/javascript">
function checkMailStatus(){
//alert("came");
var email=$("#email").val();// value in field email
$.ajax({
type:'post',
url:'checkMail.php',// put your real file name
data:{email: email},
success:function(msg){
alert(msg); // your message will come here.
}
});
}
</script>
<p>Email<input type="text" name="email" id="email" onblur="checkMailStatus()"size=18 maxlength=50 required></p>
your php: checkMail.php
你的 php: checkMail.php
$echeck="select email from register where email=".$_POST['email'];
$echk=mysql_query($echeck);
$ecount=mysql_num_rows($echk);
if($ecount!=0)
{
echo "Email already exists";
}
回答by Razorphyn
I'm not sure because I have always used JQuery, however I try:
Source: W3Schools
HTML file:
我不确定，因为我一直使用 JQuery，但是我尝试：
来源：W3Schools
HTML 文件：
<script type="text/javascript">
function checkInput(){
var email=document.getElementById('email').value.trim();
if(email.length==0)
return;
var xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
if(xmlhttp.responseText==0){
document.getElementById('email').value='';
alert('Email already exists');
}
else if(xmlhttp.responseText==1){
document.getElementById('email').value='';
alert('Invalid Email');
}
}
xmlhttp.open("GET","check.php?email="+email,true);
xmlhttp.send();
}
</script>
//I would use check mail button, to prevent accindental unfocus
<p>Email<input type="text" name="email" id="email" onblur="javascript:checkInput();" size=18 maxlength=50 required></p>
check.php
检查.php
//This is a simple input check
//The way you check the value isn't secure, you should sanitaze the input
// consider PDO or MySQLi
//Check if email otherwise stop php and clean input
if(!filter_var($_GET['email'], FILTER_VALIDATE_EMAIL)){
echo '1';
exit();
}
$echeck="select email from register where email='$_GET['email']'";
$echk=mysql_query($echeck);
$ecount=mysql_num_rows($echk);
if($ecount!=0){
echo '0';
exit();
}
else{
echo '2';
}
