thinkphp 3.2 视图模型 生成的SQL语句提示 1267异常 求指点

thinkphp 3.2 视图模型 生成的SQL语句提示 1267错误 求指点~
用的TP3.2 视图模型 查询 
模型里是这样写的 
PicViewModel.class.php

<?php<br />namespace Home\Model;<br />use Think\Model\ViewModel;<br />class PicViewModel extends  ViewModel{<br />    public $viewFields =array(<br />       'Picture'=> array('picTitle','picToken','picCategroy','picAuthor','picPostTime','_as'=>'Picture'),<br />        'PictureAttachment' =>array('pictureid','pictureurl','creattime','_on'=>'Picture.picToken = PictureAttachment.pictureid','_as'=>'PictureAttachment'),<br /><br /><br />    );<br />}<br />

控制器这样写

  public function  Pic(){<br />         $PicModel =D('PicView');    <br />        $s1= $PicModel->field('picTitle,picCategroy,picAuthor,picPostTime,pictureurl')->order('picPostTime desc')->select();<br />        dump($PicModel->getLastSql());<br />        dump($s1);<br /><br />    }

生成的SQL 语句是这样的

SELECT Picture.picTitle AS picTitle,Picture.picCategroy AS picCategroy,Picture.picAuthor AS picAuthor,Picture.picPostTime AS picPostTime,PictureAttachment.pictureurl AS pictureurl FROM xxx_picture Picture  JOIN xxx_picture_attachment PictureAttachment ON Picture.picToken = PictureAttachment.pictureid ORDER BY Picture.picPostTime desc

在phpmyadmin里运行出现
MySQL 返回： 文档

#1267 - Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '=' 
这个应该是排序规则不同  然后我在phpmyadmin里直接修改表的
改成一样是utf8_general_ci,了 还是报错 

网上查了是这样执行
alert xxx_picture_attachment CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci
ALTER xxx_picture_attachment DEFAULT CHARACTER SET utf8_general_ci
貌似也不行额
报错
MySQL 返回： 文档

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'alert xxx_picture_attachment CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_' at line 1 

求大神指点下啊
------解决思路----------------------
贴出表结构看看