这里使用字符串形式 与关键字冲突的风险 SELECT * FROM `weibo_user` WHERE ( id>1 ) ORDER BY id DESC LIMIT 2   var_dump($user->where('id>1')->order('id DESC')->limit(2)->select());   数组形式 避免了关键字冲突 SELECT * FROM `weibo_user` WHERE `id` = '1' ORDER BY `create` DESC LIMIT 2   var_dump($user->where(array('id'=>array('eq','1')))->order(array('create'=>'DESC'))->limit(2)->select());     CURD 操作   显示一条数据 SELECT * FROM `weibo_user` WHERE ( id in (1,2,3) ) LIMIT 1   var_dump($user->where('id in (1,2,3)')->find());   删除一条数据 DELETE FROM `weibo_user` WHERE ( id=42 )   $user->where('id=42')->delete();   条件查询 SELECT * FROM `weibo_user` WHERE `id` = 1 AND ( username="蜡笔小新" )   多个where使用时 尽量使用变量形式，否则为引起冲突   $map['id']=1;   var_dump($user->where($map)->where('username="蜡笔小新"')->select()); 字符串形式排序SELECT * FROM `weibo_user` ORDER BY id DESC   var_dump($user->order('id DESC')->select()); 数组形式排序 SELECT * FROM `weibo_user` ORDER BY `id` DESC   var_dump($user->order(array('id'=>'DESC'))->select()); 多列字符串形式排序 SELECT * FROM `weibo_user` ORDER BY id DESC,email DESC   var_dump($user->order('id DESC,email DESC')->select());   多列数组形式排序 SELECT * FROM `weibo_user` ORDER BY `id` DESC,`email` DESC   var_dump($user->order(array('id'=>'DESC','email'=>'DESC'))->select());   字段投影      SELECT `id`,`username` FROM `weibo_user`   dump($user->field('id,username')->select());   字段投影      SELECT sum(id) AS count FROM `weibo_user`  将字段名称 作为别名处理   dump($user->field('sum(id) AS count')->select());   字段投影  截取前3位字符，并作别名处理SELECT `id`,LEFT(username,3) AS `left_username` FROM `weibo_user`   dump($user->field(array('id','LEFT(username,3)'=>'left_username'))->select()); 获取所有字段 field() 和 field('*')和效果相同   dump($user->field('*')->select())     ; 写入操作   $user->field('id,email')->create();   limit SELECT * FROM `weibo_user` LIMIT 2   dump($user->limit(2)->select());   SELECT * FROM `weibo_user` LIMIT 2,3   dump($user->limit(2,3)->select());   page SELECT * FROM `weibo_user` LIMIT 4(页码数据),2(显示条数)   dump($user->page(3,2)->select());   table 表切换 SELECT * FROM `weibo_topic`   dump($user->table('weibo_topic')->select());   简化表名   SELECT * FROM `weibo_topic` __TOPIC__ => 'weibo_topic'   dump($user->table('__TOPIC__')->select());   多表查询  SELECT * FROM weibo_user a,weibo_topic b   dump($user->table('__USER__ a,__TOPIC__ b')->select());   数组形式多表查询避免关键字冲突 SELECT a.id,b.id FROM `weibo_user` `a`,`weibo_topic` `b`   dump($user->field('a.id,b.id')->table(array('weibo_user'=>'a','weibo_topic'=>'b'))->select());