输入类型日期,用于设置从数据库中获取的日期

I have database user consist of attribute like name,password,dob and etc. datatype is used to store date is date.while updating, I used to fetch like below

$query="select * from user where email='$user'";
$res=mysqli_query($conn,$query);
$fet=mysqli_fetch_array($res);

<input type="date" id="dob" name="dob" value="<?php if($fet['dob']==00-00-0000){ }else{ echo date($fet['dob']);} ?>">

I want date which is to fetch from database to this above input type date.

EDIT:
As I understood in comments of my answer, you are storing DATETIME values in your database and not DATE values. Here is how to get a date format from a datetime format using DateTimeclass:

$dob = new DateTime($fet['dob']);
$formatted = $dob->format('Y-m-d');

To output it in short syntax in your <input>:

<?php
$dob = (new DateTime($fet['dob']))->format('Y-m-d');
?>
<input type="date" id="dob" name="dob" value="<?php echo $dob; ?>">

Issues:
An <input type="date"> should have a value in the YYYY-MM-DD format.
The date() function expects a format and a timestamp.
You did not quote the 00-00-0000 value.

You won't need to format your date string as its format is right for your input:

<input type="date" id="dob" name="dob" value="<?php echo $fet['dob']; ?>">

If you need to manipulate dates in PHP I would recommend the DateTime class.

This should be a comment, but its a bit long.

I used to fetch like below

What you've shown is not valid PHP - it won't work. PHP will tell you when stuff is not working and why if your error logging/reporting is configured correctly.

input type="date"

I presume you are aware this has very limited support in browsers

select *

Generally its a very bad idea not to be specific about what you are selecting from a database, and particularly so in this scenario. Even if the underlying data type for the dob is a date, you should do an explicit format on it to get it into the right form for the later processing (in this case, injecting it as the value of the input)