mysql 常用系统指令

show variables like '%dir%';
show variables

CREATE TABLE `App` (
  `Id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '主键',
  `AppId` varchar(500) NOT NULL DEFAULT 'default' COMMENT 'AppID'
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COMMENT='应用表';