mysql在升到php7后，原有的mysql_*函数都没有了，如果要迁移，可以参考 这一篇：https://stackoverflow.com/questions/36073703/mysql-to-pdo-comparison-table

介绍的比较详细，比如mysql常用的几个函数的转换写法，这里都有了：
随便截一点内容，详细的还是去网站看：

MySQL_ Original Driver to PDO Comparative Table

Introduction:

This table is not intended to be a tutorial or a guide to PDO, but to provide a correspondence between MySQL_ and PDO. So, some important PDO commands are missing, if they don't have a MySQL_ correspondence.

Among these omitted commands, there is a major PDO feature, the prepared statements. I strongly recommend to use it, also if only cited in this guide.

This is a very extended answer. I'm sorry for the low quality of spelling (I'm not english) and for the typos. I will try to correct and improve it in the next few days. Any suggestion or contribution is welcome.

Naming Conventions:

To avoid misunderstanding, in this answer I use:

In PDO, we have two major object types, the PDOObject (the connection between PHP and a database server) and the PDOStatement (a prepared statement and, after the statement is executed, an associated result set). In this answer, variable names are:

  • $dbh, refer to PDOobject;
  • $stmt, refer to PDOStatement.