dbase_open() opens a dBase database with the given access mode.
当安全模式被激活时，PHP 将检查被操作的文件或者目录是否与正在执行的脚本有相同的 UID（所有者）。
本函数受 open_basedir 的影响。
The name of the database. It can be a relative or absolute path to the file where dBase will store your data.
An integer which correspond to those for the open() system call (Typically 0 means read-only, 1 means write-only, and 2 means read and write).
You can't open a dBase file in write-only mode as the function will fail to read the headers information and thus you can't use 1 as mode.
Returns a database link identifier if the database is successfully opened,
FALSE if an error occurred.