不要重新发明***。您所需要的已经存在的几乎是现成的：

Do not reinvent the wheel. What you need already exists almost out-of-the-box:

<?php
    $result = exec("/path/to/mysqldump -u$username -p$password your_database your_table > /desired/output/path/dump.sql");

您可能想检查 $ result afterwads，以确保一切顺利。

You may want to check the contents of $result afterwads, to make sure everything went smooth.

此处的参考手册。