Insert HTML input using ajax. Something wrong with code - php

Question

If I click on submit button using only php, data are recorded in mysql.
Through ajax _autosave.php only update works. Insert does not work. going crazy.... can not understand
ajax code in first.php
<script type="text/javascript">
$(document).ready(function() {
setInterval(function (){
var date_day1=$("#date_day1").val();
var amount1=$("#amount1").val();
DATA = 'date_day1=' + date_day1 + '&amount1=' + amount1;
$.ajax({
type: "POST",
url: "_autosave.php",
data: DATA,
cache: false,
/*success: function(){
$(".done").show().html("Saved as a draft!");
}*/
});
setTimeout(function(){
$(".done").hide();
}, 1000);// 15 seconds
}, 3000);// 1 minute
});
</script>
HTML input
<td><input type="text" name="date_day1" id="date_day1" value="<?php echo $_POST['date_day1']?>" size="1"></td>
<td><input type="text" name="amount1" id="amount1" value="<?php echo $_POST['amount1']?>" size="5"></td>
Part of php code that is identical in first.php and _autosave.php
$date_day1 = $_POST['date_day1'];
$amount1 = $_POST['amount1'];
if ($stmt = mysqli_prepare($mysqli, "SELECT RecordDay FROM 2_1_journal WHERE RecordDay = ? ")) {
$stmt->bind_param('s', $date_day1);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($RecordDay);
$stmt->fetch();
//echo $RecordDay .' $RecordDay<br>';
}
if ($RecordDay == $date_day1) {
if ($stmt = mysqli_prepare($mysqli, "UPDATE 2_1_journal SET Amount = ? WHERE RecordDay = ? ") ) {
$stmt->bind_param( 'ds', $amount1 , $date_day1 );
$stmt->execute();
/*echo $date_day1 .' date_day1<br>';
echo $amount1 .' amount1<br>';*/
}
}
else {
if ($stmt = mysqli_prepare($mysqli, "insert into 2_1_journal
(RecordDay, Amount, DebitAccount, CreditAccount)
values(?,?,?,? )")) {
$stmt->bind_param('sdss', $date_day1, $amount1, $debit1, $credit1 );
$stmt->execute(); //execute above insertion
}
}
Update works in both files (called from both files). Insert works only if called without ajax. What is wrong?
Update
Finally found what was wrong. If $_POST is not set (not send), nothing is recorded in mysql. However no error message after execution. Simply need to remember that all variables here $stmt->bind_param('sdss', $date_day1, $amount1, $debit1, $credit1 ); must exist.

Answer 1

The data syntax might be the reason, use this format:
data: { key1: "value1", key2: "value2" }
See this example from: http://api.jquery.com/jQuery.ajax/
$.ajax({
type: "POST",
url: "some.php",
data: { name: "John", location: "Boston" }
})
so, for your case try:
$.ajax({
type: "POST",
url: "_autosave.php",
data: {date_day1:$("#date_day1").val(), amount1: $("#amount1").val()},
cache: false,
});

Answer 2

in insert you binding 5 parameters instead of 4