我在 html 選擇表單上使用多重選擇，目的是在一次銷售中插入兩個 id。我收到此錯誤：Notice: Array to string conversion in C:\xampp\htdocs\allprojects\projects\Colégios\users\teacher\addscore.php on line 33insert into cursosprogramas (departamento, codigocurso, diurno, contacto, pos_laboral, contacto2, proc_por) values ('100', '120','Array', '88839', '7', '5353','2')Query failed.代碼：<select type=text name=diurno[] value="<?php echo $name; ?>" multiple size=2><br>    <?php    $sql = "select * from professore1 where coordenacao='$coordenacao' order by coordenacao;";    for ($i= 0; $i < pg_numrows($res);$i++) {        $name = pg_fetch_result ($res, $i, "name");        $numero = pg_fetch_result ($res, $i, "numero");        echo "<option value = '$numero'>$name</option>";    }    ?></select><?php$idd=$_SESSION['jpgwapo'];$id=$_POST['id'];$grdid=$_POST['grdid'];$diurno=$_POST['diurno'];   $contacto=$_POST['contacto'];$pos_laboral=$_POST['pos_laboral'];$contacto2=$_POST['contacto2'];$con = @pg_connect ("port=5432 host=localhost dbname=postgres user=postgres password=a");$sql = "insert into cursosprogramas (departamento, codigocurso, diurno, contacto, pos_laboral, contacto2, proc_por) values ('$id', '$grdid','$diurno', '$contacto', '$pos_laboral', '$contacto2','$idd')";$res = @pg_query ($con, $sql);if ($res == NULL){    echo "Query failed.";    exit (0);}   ?>到目前為止，我已經嘗試遵循一些示例，但我仍然不明白它是如何工作的。