mysqli_query() expects at least 2 parameters, 1 given

Well hello, I’m just trying to update (add 1) to the “receiptno” field in “numbers”
table and display the new receiptno. At a loss
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the code:
SEMrush

<?php
//Open a new connection to the MySQL server
require_once “getprerentdb.php”;
echo “<center>”;echo date(‘m/d/y’);
$id=”id”;
$receiptno = “receiptno +1”;
$sql = “UPDATE numbers SET
receiptno=’$receiptno’ Where id='”.$_POST(‘id’).”‘”;
mysqli_query($sql) or die(mysql_error());
echo “Record for receiptno “.$_POST(“receiptno”).” has been updated”;
echo “receiptno “.$_POST(“receiptno”).” “;
?>
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errors:

Notice: Undefined index: id on line 8

Warning: mysqli_query() expects at least 2 parameters, 1 given on line 9

Fatal error: Uncaught Error: Call to undefined function mysql_error() on line 9