Conditional insert or update in mysql - php

Question

I have a table with input of type time and I want to check first if there is a row with the current date and the id of employee, if it was I update the value of the input if not I insert a new row. This is what I have tried but it always inserts a new row even if the condition exists:
<?php
$E1=$_POST['E1'];
$connect = mysqli_connect("localhost", "root", "ntr-ktb123", "absence");
$sql1="SELECT * FROM retards WHERE Date ='Curdate()' AND
IdEmpl='".$_POST["IdEmp"]."' ;";
$result1=mysqli_query($connect,$sql1);
if(!$result1){
die('ERREUR SQL ! <br>'.$sql.'<br>'.mysqli_error());}
if($dt=mysqli_fetch_array($result1,MYSQLI_ASSOC)){
$sql="update retards set E1='$E1' where IdEmpl='".$_POST["IdEmp"]."' AND
Date=CURDATE();";
}
else{
$sql="insert into retards(IdEmpl,Date,E1) values
('".$_POST["IdEmp"]."',CURDATE(),'$E1'); ";
}
$result = mysqli_query($connect, $sql);
if (!$result)
{
echo("Error description: " . mysqli_error($connect));
}
else {
$message ="Effectué avec succès!";
echo "<script type='text/javascript'>alert('$message'); </script>";
}
mysqli_close($connect);
?>

Answer 1

This is known as an upsert which can be done in mysql using the insert ... on duplicate key update syntax.
insert into t (a, b, c) values (?, ?, ?)
on duplicate key update b = ?
Your table should have an appropriate unique index or primary key defined on the column(s) of interest.