PHP的extension_dir设置问题

PHP安装时，extension_dir的路径要设成绝对路径：extension_dir = "D:/Tools/php-7.0.5/ext"，

不然如果设成extension_dir = "ext"相对路径，会导致报错：Fatal error: Uncaught Error: Call to undefined function mysqli_connect()，

同时thinkphp项目会报Undefined class constant 'MYSQL_ATTR_INIT_COMMAND'