PHP code

<?php
$user_id = $_POST['user_id'];
$shift = $_POST['text'];
$conn = mysqli_connect();
$sql = "SELECT Position FROM tablename WHERE UserID=?";
$stmt = mysqli_prepare($conn, $sql);
mysqli_stmt_bind_param($stmt, "s", $user_id);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_bind_result($stmt);
while ($row = mysqli_fetch_row($result)) {
    $position = $row[0];
}
mysqli_stmt_close($stmt);
$sqlfirst = "SELECT Code,Day,Work,Comments,Shift,Position,UserID FROM tablename2 WHERE Command = 'Request' AND UserID != :userID";
switch ($position) {
    case "Office":
        $sql1 = " AND Position IN ('Office', 'OfficeManager') AND Comments NOT LIKE '%manage%'";
        break;
    case "OfficeManager":
        $sql1 = " AND Comments NOT LIKE '%Exam%'";
        break;
    case "Manager":
        $sql1 = " AND ((Position = 'OfficeManager' AND Comments LIKE '%Manager%') OR (Position LIKE 'Manager%' AND          Comments NOT LIKE '%exam%'))";
        break;
    case "ExamManager":
        $sql1 = " AND (Position LIKE 'Manager%') OR (Position = 'OfficeManager' AND Comments LIKE '%manager%')";
        break;
}
switch ($shift) { // This variable comes straight from user input
    case "E":
    case "Earlies":
        $sql2 = " AND Shift='Earlies'";
        $shift = "earlies";
        break;
    case "L":
    case "Lates":
        $sql2 = " AND Shift='Lates'";
        $shift = "lates";
        break;
    case "":
        $sql2 = "";
        $shift = "earlies and lates";
        break;
    default:
        $err = "You can only choose between early and late shifts.\nIf you *do not* have a preference, please leave the field blank";
        break;
}
$sqlsecond = " ORDER BY Day ASC";
$sqlfinal = $sqlfirst . $sql1 . $sql2 . $sqlsecond;
?>