function performSQLUpdate($tableName, $idFieldName, $fields)
{
    $conn = $GLOBALS["connection"];
    $sql = "UPDATE " . $tableName . " SET ";
    if ($fields != NULL) {
        foreach ($fields as $key => $value) {
            if (!is_numeric($key) and $key != $idFieldName) {
                if ($value != NULL) {
                    $updateClause[] = $key . "='" . $value . "'";
                } else {
                    $updateClause[] = $key . "=NULL";
                }
            }
        }
        $sql = $sql . implode(",", $updateClause);
    }
    $sql = $sql . " WHERE " . $idFieldName . "='" . $fields[$idFieldName] . "';";
    $result = mysqli_query($conn, $sql);
    if (!$result) {
        echo mysqli_error($conn);
        printCallstackAndDie();
    }
    return TRUE;
}
function GetEmployeeCount(&$totalEmployees, &$employeesWithNoMainVacation)
{
    $conn = $GLOBALS["connection"];
    $sql = "SELECT COUNT(*) FROM " . EMPLOYEE_TABLE;
    $result = mysqli_query($conn, $sql);
    if (!$result) {
        printCallstackAndDie();
    }
    $data = mysqli_fetch_array($result);
    $totalEmployees = $data[0];
    $sql = "SELECT COUNT(*) FROM " . EMPLOYEE_TABLE . " WHERE mainVacationRequestID " . "IS NULL";
    $result = mysqli_query($conn, $sql);
    if (!$result) {
        printCallstackAndDie();
    }
    $data = mysqli_fetch_array($result);
    $employeesWithNoMainVacation = $data[0];
}
function GetAbsenceTypeCount()
{
    $conn = $GLOBALS["connection"];
    $sql = "SELECT COUNT(*) FROM " . ABSENCE_TYPE_TABLE;
    $result = mysqli_query($conn, $sql);
    if (!$result) {
        printCallstackAndDie();
    }
    $count = mysqli_num_rows($result);
    return $count;
}