转载自：http://www.yiichina.org/forum/thread-218-1-1.html
这里提供一些yii的方法解析,希望能够对新手有一点帮助:
1. 存取数据库方法
存储第一种（SAVE ）
存表时候用到
例子：
$post=new Post;
$post->title='sample post';
$post->content='content for the sample post';
$post->createTime=time();/$post->createTime=new CDbexpression_r('NOW()');
$post->save();
$user_field_data= new user_field_data;
$user_field_data->flag=0;
$user_field_data->user_id=$profile->id;
$user_field_data->field_id=$_POST['emailhiden'];
$user_field_data->value1=$_POST['email'];
$user_field_data->save(); //注：当一个表存储4次的时候，需要创建4个handle new4次
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存储第二种（存储）
存储后我们需要找到这条记录的流水id 这样做 $profile = new profile; $profile->id;
存储第三种 用于更加安全的方法，来绑定变量类型 这样可以在同一个表中存储两个记录
$sql="insert into user_field_data(user_id,field_id,flag,value1) values(:user_id,:field_id,:flag,:value1);";
$command=user_field_data::model()->dbConnection->createCommand($sql);
$command->bindParam(":user_id",$profile->id,PDO::PARAM_INT);
$command->bindParam(":field_id",$_POST['firstnamehiden'],PDO::PARAM_INT);
$command->bindParam(":flag",$tmpflag,PDO::PARAM_INT);
$command->bindParam(":value1",$_POST['firstname'],PDO::PARAM_STR);
$command->execute();
$command->bindParam(":user_id",$profile->id,PDO::PARAM_INT);
$command->bindParam(":field_id",$_POST['emailhiden'],PDO::PARAM_INT);
$command->bindParam(":flag",$tmpflag,PDO::PARAM_INT);
$command->bindParam(":value1",$_POST['email'],PDO::PARAM_STR);
$rowchange = $command->execute();
// 用来判断
if( $rowchange != 0){ 修改成功 }
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注：update delete都可以用这个方法
$sql="delete from profile where id=:id";
$command=profile::model()->dbConnection->createCommand($sql);
$command->bindParam(":id",$userid,PDO::PARAM_INT);
$this->rowflag=$command->execute();
$sql="update profile set pass=:pass,role=:role where id=:id";
$command=profile::model()->dbConnection->createCommand($sql);
$command->bindParam(":pass",$password,PDO::PARAM_STR);
$command->bindParam(":role",$role,PDO::PARAM_INT);
$command->bindParam(":id",$userid,PDO::PARAM_INT);
$this->rowflag=$command->execute(); // 同理变更updateAll()模式
$sql="update user_field_data set flag = :flag where user_id= :user_id and field_id= :field_id ";
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//原始sql语句
$criteria = new CDbCriteria;
$criteria->condition = 'user_id = :user_id and field_id= :field_id';
$criteria->params = array(':user_id' => $userid,':field_id' => $fieldid);
$arrupdate = array('flag' => $flag);
if(user_field_data::model()->updateAll($arrupdate,$criteria) != 0)
{
//更新成功后。。。
}
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第四种更新和存储应用同一个handle 流程：先查询记录是否存在，若存在就更新，不存在就新创建
注：1.第一次查询的变量，要跟save()前的变量一致。
2.存储时候需要再次 new一下库对象 $user_field_data = user_field_data::model()->findByAttributes(
$attributes = array('user_id' => Yii::app()->user->user_id, 'field_id' => $key));
if ($user_field_data !== null)
{
$user_field_data->value1 = $value;
$user_field_data->save();
}
else
{
$user_field_data = new user_field_data;
$user_field_data->user_id = Yii::app()->user->user_id;
$user_field_data->field_id = $key;
$user_field_data->value1 = $value;
$user_field_data->save();
}
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2、查询数据
注：当项目没查找到整个对象会为空需要这样判定
if($rows !== null) 当对象不为空
{
return true;
}else{
return false;
}
SELECT
读表时候用到
第一种find()
// find the first row satisfying the specified condition
$post=Post::model()->find($condition,$params);
// find the row with postID=10
$post=Post::model()->find('postID=:postID', array(':postID'=>10)); 同样的语句，用另种方式表示
$criteria=new CDbCriteria;
$criteria->select='title'; // only select the 'title' column
$criteria->condition='postID=:postID';
$criteria->params=array(':postID'=>10);
$post=Post::model()->find($criteria); // $params is not needed 第二种 find()
$post=Post::model()->find(array(
'select'=>'title',
'condition'=>'postID=:postID',
'params'=>array(':postID'=>10),
)); // find the row with the specified primary key
$post=Post::model()->findByPk($postID,$condition,$params);
// find the row with the specified attribute values
$post=Post::model()->findByAttributes($attributes,$condition,$params);
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示例：第一种 findByAttributes()
$checkuser = user_field_data::model()->findByAttributes(
array('user_id' => Yii::app()->user->user_id, 'field_id' => $fieldid));
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第二种 findByAttributes()
$checkuser = user_field_data::model()->findByAttributes(
$attributes = array('user_id' => Yii::app()->user->user_id, 'field_id' => $fieldid));
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第三种 当没有conditions时候，不用params
$user_field_data = user_field_data::model()->findAllByAttributes(
$attributes = array('user_id' => ':user_id'),
$condition = "field_id in (:fields)",
$params = array(':user_id' => Yii::app()->user->user_id, ':fields' => "$rule->dep_fields"));
// find the first row using the specified SQL statement
$post=Post::model()->findBySql($sql,$params);
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例子
user_field_data::model()->findBySql("select id from user_field_data where user_id = :user_id and field_id = :field_id ", array(':user_id' => $userid,':field_id'=>$fieldid));
此时回传的是一个对象
第四种 添加其他条件
http://www.yiiframework.com/doc/api/CDbCriteria#limit-detail
$criteria = new CDbCriteria;
$criteria->select ='newtime'; //选择只显示哪几个字段要与库中名字相同，但是不能COUNT(newtime) as name这样写
$criteria->join = 'LEFT JOIN Post ON Post.id=Date.id';
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1. 先要在relation函数中增加与Post表的关系语句
2. Date::model()->with('post')->findAll($criteria)
$criteria->group = 'newtime';
$criteria->limit = 2; // 都是从0开始，选取几个
$criteria-> offset = 2;// 从哪个偏移量开始
print_r(Date::model()->findAll($criteria));
得到行数目或者其他数目 count
// get the number of rows satisfying the specified condition
$n=Post::model()->count($condition,$params);
// get the number of rows using the specified SQL statement
$n=Post::model()->countBySql($sql,$params);
// check if there is at least a row satisfying the specified condition
$exists=Post::model()->exists($condition,$params);
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3、更新（UPDATE）
例子：
$post=Post::model()->findByPk(10);
$post->title='new post title';
$post->save(); // save the change to database
// update the rows matching the specified condition
Post::model()->updateAll($attributes,$condition,$params); 例子：或者参考上面例子
$c=new CDbCriteria;
$c->condition='something=1';
$c->limit=10;
$a=array('name'=>'NewName');
Post::model()->updateAll($a, $c);
// update the rows matching the specified condition and primary key(s)
Post::model()->updateByPk($pk,$attributes,$condition,$params); 例子
$profile = profile::model()->updateByPk(
Yii::app()->user->user_id,
$attributes = array('pass' => md5($_POST['password']), 'role' => 1));
// update counter columns in the rows satisfying the specified conditions
Post::model()->updateCounters($counters,$condition,$params);
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4、删除（DELETE）
例子：
$post=Post::model()->findByPk(10); // assuming there is a post whose ID is 10
$post->delete(); // delete the row from the database table
// delete the rows matching the specified condition
Post::model()->deleteAll($condition,$params);
// delete the rows matching the specified condition and primary key(s)
Post::model()->deleteByPk($pk,$condition,$params);
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5、比较（COMPARE）
目前可以取出的
1. $allquestion=field::model()->findAllBySql("select label from field where step_id = :time1 ", array(':time1' =>1));
2.
$criteria=new CDbCriteria;
$criteria->select='label,options';
$criteria->condition='step_id=:postID';
$criteria->params=array(':postID'=>1);
$allquestion=field::model()->findAll($criteria);
$allquestion=field::model()->find("",array("label"));
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可以与在models文件夹中的 库连接文件relations()函数合用，这样可以联合查询
$criteria=new CDbCriteria;
$criteria->condition='field.step_id=1';
$this->_post=field::model()->with('step')->findAll($criteria);
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这样出来的数组里面包含step表中的值，且这个值的条件为 step.id=field.step_id
public function relations()
{
return array(
'step'=>array(self::BELONGS_TO, 'step', 'step_id'),
);
}
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