ThinkPHP
ThinkPHP CURD方法的limit方法也是模型类的连贯操作方法之一,主要用于指定查询和操作的数量,特别在分页查询的时候使用较多。并且ThinkPHP的limit方法可以兼容所有的数据库驱动类。
其具体用法如下:
1.限制结果数量:
例如获取满足要求的10个用户,如下调用即可:
$User = M('User'); $User->where('status=1')->field('id,name')->limit(10)->select();
limit方法也可以用于写操作,例如更新满足要求的3条数据:
$User = M('User'); $User->where('score=100')->limit(3)->save(array('level'=>'A'));
2.分页查询:
用于文章分页查询是limit方法比较常用的场合,例如:
$Article = M('Article'); $Article->limit('10,25')->select();
表示查询文章数据,从第10行开始的25条数据(可能还取决于where条件和order排序的影响 这个暂且不提)。
在3.1版本后,你也可以这样使用:
$Article = M('Article'); $Article->limit(10,25)->select();
另外,对于大数据表,尽量使用limit限制查询结果,否则会导致很大的内存开销和性能问题。

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