我是使用sqlite3处理html和php的初学者。我在网上找不到解决方案，当我执行insert语句时，它不会被插入。
任何提示都有助于解决此问题。updatec是来自不同html文件的单选按钮条目。

if($updateC == 'Insert') {
      $sql = "INSERT INTO MANGA_BOOK (Title,Author,Genre,ISBN_number,Age_rating,Language,Book_review,Price)
              VALUES ('$Btitle', '$BAuthor', '$BGenre', '$BISBN', '$age', '$lan', '$bookRev', '$pr')";
      $enterInto = $db->exec($sql);

      $sql2 = "INSERT INTO SELLS (M_ISBN, S_ID, Copies) VALUES ('$BISBN', '$storeNum', '$cop')";
      $enterInto2 = $db->exec($sql2);
    } 

    $rowCount = $db->querySingle("SELECT COUNT(*) FROM SELLS");
    $sql = "SELECT DISTINCT Title, Author, ISBN_number, Copies, S_ID
            FROM MANGA_BOOK 
            NATURAL JOIN SELLS
            ORDER BY S_ID";
    $results = $db->query($sql);

    if($rowCount > 0) {
      echo '<table> <tr>';
      echo '<th>Title</th>';
      echo '<th>Author</th>';
      echo '<th>ISBN_number</th>';
      echo '<th>Copies</th>';
      echo '<th>S_ID</th>';
      echo '</tr>';

      while($row = $results->fetchArray()) {
        echo '<tr>', '<td>', $row["Title"], '</td>',
        '<td>', $row["Author"], '</td>',
        '<td>', $row["ISBN_number"], '</td>',
        '<td>', $row["Copies"], '</td>',
        '<td>', $row["S_ID"], '</td>', '</tr>';
      }
      echo '</table>';
    } else {
      echo "Error in fetching database";
    }