zhangxiaojian

问下是哪篇文章 ？

对列为空的话，m_last 指向 m_first 的地址，*m_last = first 相当于 m_first = first. 两个值相等，但都不为 NULL

Hi, @XUZHOUWANG , Please check if the file "plugin.frm" exists in DATADIR/mysql . If not, you can try to use [mysql_upgrad](https://dev.mysql.com/doc/refman/5.6/en/mysql-upgrade.html) to reinstall or use [mysql_install_db](https://dev.mysql.com/doc/refman/5.6/en/mysql-install-db.html) to initial your DATADIR.