<?php class Car { var $color = "add"; function Car($color="green") { $this->color = $color; } function what_color() { return $this->color; } } $car = new Car; echo $car->what_color(),"<br>over"; ?> PHP版本号
使用mysql5.7版本的mysqldump命令执行备份mysql8.0版本的数据库时会报错: mysqldump: Couldn't execute 'SET SQL_QUOTE_SHOW_CREATE=1/*!40102 ,SQL_MODE=concat(@@sql_mode, _utf8 ',NO_KEY_OPTIONS,NO_TABLE_OPTIONS,NO_FIELD_OPTIONS') */': Variable 'sql_mode' can't be set to the valu