How to detect duplicate values in session array php?

[israel Parajes]

im creating a student subject reservation that will add subject from a table row.I would like to detect the presence of duplicate values,then echo if the values are detected.

For example this is the click event:

$i=0;
$b =1;
while($row=mysql_fetch_assoc($sql) ){


echo "<tr><td>".$row['Subject']."<input type='hidden' name='subj[$i]' value=".$row['Subject']."></td>
<td>".$row['Lec']."<br/>".$row['Lab']."<input type='hidden' name='leclab[$i]' value=".$row['Lec']."><input type='hidden' name='lab[$i]' value=".$row['Lab']."></td>

<td>".$row['Descriptive']."<input type='hidden' name='desc[$i]' value=".$row['Descriptive']."></td>
<td>".$row['Day']."<br/>".$row['Labday']."<input type='hidden' name='daylabday[$i]' value=".$row['Day']."><input type='hidden' name='labday[$i]' value=".$row['Labday']."></td>

<td>".$row['LecTime']."<br/>".$row['LabTime']."<input type='hidden' name='lectlabt[$i]' value=".$row['LecTime']."><input type='hidden' name='labtime[$i]' value=".$row['LabTime']."></td>

<td>".$row['Room']."<br/>".$row['Labroom']."<input type='hidden' name='roomlabroom[$i]' value=".$row['Room']."><input type='hidden' name='labroom[$i]' value=".$row['Labroom']."></td>

<td><input id='send' name='reserv[$i]' type='submit' value='Add' onclick='addRow('myTable')' /> </td></tr>";

$i++;


}
}

and this is the code for the displaying in the table row

$c=0;

        while($c<=$counter){
            if($_SESSION["S['$c']"]==""){
            echo "-";
            }
        $array1=array($_SESSION["lect['$c']"],$_SESSION["labt['$c']"],$_SESSION["Day['$c']"] ,$_SESSION["lday['$c']"]);
        if(count(array_unique($array1))<count($array1)){
            echo "Duplicate entry found in array";
        }
        else{
                    echo "<tr><td>".$_SESSION["S['$c']"] . " </td>
                <td>".$_SESSION["lec['$c']"] . "<br/>".$_SESSION["lab['$c']"] . "</td>
                <td>".$_SESSION["lect['$c']"] . "<br/>".$_SESSION["labt['$c']"] . "</td>
                <td>".$_SESSION["Day['$c']"] . "<br/>".$_SESSION["lday['$c']"] . "</td>
                <td>".$_SESSION["room['$c']"] . "<br/>".$_SESSION["lroom['$c']"] . "</td></tr><br>";
             $unit=$_SESSION["lec['$c']"] + $_SESSION["lab['$c']"];
               $units= $units+$unit;
        }

the problem is how to detect if i add duplicate value
sorry for my bad English.
thanks in advance

[Dormilich]

it depends on the definition of "duplicate value" and if you need them. to prevent having two (or more) identical SQL results, simply use SELECT DISTINCT … FROM ….

arrays can be treated similarly by applying array_unique().