Detailed examples of Yii model query techniques based on arrays and objects, yiimodel_PHP tutorial

Detailed examples of Yii's array- and object-based Model query techniques, yiimodel

This article describes Yii's array- and object-based Model query techniques with examples. Share it with everyone for your reference, the details are as follows:

For a Model Post, there are the following 4 query methods, which return objects or object arrays.

//查找满足指定条件的结果中的第一行 find the first row satisfying the specified condition
$post=Post::model()->find($condition,$params);
//查找具有指定主键值的那一行 find the row with the specified primary key
$post=Post::model()->findByPk($postID,$condition,$params);
//查找具有指定属性值的行 find the row with the specified attribute values
$post=Post::model()->findByAttributes($attributes,$condition,$params);//未找到返回null
//通过指定的SQL 语句查找结果中的第一行 find the first row using the specified SQL statement
$post=Post::model()->findBySql($sql,$params);

If the find method finds a row that meets the query conditions, it will return a Post instance whose attributes contain the values ​​of the corresponding columns in the data table row. Then we can read the loaded value like a normal object property, such as echo $post->title;. The find method will return null if nothing is found in the database using the given query criteria.

When calling find, we use $condition and $params to specify the query conditions. Here $condition can be a WHERE string in the SQL statement and $params is an array of parameters whose values ​​should be bound to the placeholders in $condation. For example: Suppose we query the data with postID = 10

// find the row with postID=10
$post=Post::model()->find('postID=:postID', array(':postID'=>10));

The condition $condition is the where part in our sql. What about the parameters? They are passed through params, but the name is added with ":".

YII has a CDbCriteria class to construct queries. If we query the title with a postId of 10, CdbCriteria is constructed like this

$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

An alternative to CDbCriteria is to pass an array to the find method. The keys and values ​​of the array respectively correspond to the attribute names and values ​​of the criterion. The above example can be rewritten as follows:

$post=Post::model()->find(array(
  'select'=>'title',
  'condition'=>'postID=:postID',
  'params'=>array(':postID'=>10),
));

Of course also applies to findAll()

self::$_items[$type]=array();
$models=self::model()->findAll(array(
  'condition'=>'type=:type',
  'params'=>array(':type'=>$type),
  'order'=>'position',
));

When a query condition is about matching several columns by specified values, we can use findByAttributes(). We make the $attributes parameter an array of values ​​indexed by column name.
$attributes in findByAttributes is the name of the field. How to query if the title is abc? See below
Copy code The code is as follows: Post::model()->findByAttributes(array('title'=>'abc'))

Other methods:

1. $admin=Admin::model()->findAll($condition,$params);

This method is to query a collection based on a condition, such as:
Copy code The code is as follows: findAll("username=:name",array(":name"=>$username));
2. $admin=Admin::model()->findAllByPk($postIDs,$condition,$params);
findAllByPk($id,"name like ':name' and age=:age" ,array(':name'=>$name,'age'=>$age));
This method is to query a collection based on the primary key. Multiple primary keys can be used, such as:
Copy code The code is as follows: findAllByPk(array(1,2));
3. $admin=Admin::model()->findAllByAttributes($attributes,$condition,$params);

This method is to query a collection based on conditions, which can be multiple conditions. Put the conditions into an array, such as:
Copy code The code is as follows: findAllByAttributes(array('username'=>'admin'));
4. $admin=Admin::model()->findAllBySql($sql,$params);

This method is to query an array based on a SQL statement, such as:
Copy code The code is as follows: findAllBySql("select *from admin where username=:name",array(':name'=>'admin'));

2. Method of querying objects

1. $admin=Admin::model()->findByPk($postID,$condition,$params);

Query an object based on the primary key, such as: Copy code The code is as follows: findByPk(1);
2. $row=Admin::model()->find($condition,$params);

Query a set of data based on a condition, there may be multiple data, but it only returns the first row of data, such as:
Copy code The code is as follows: find('username=:name',array(':name'=>'admin'));
3. $admin=Admin::model()->findByAttributes($attributes,$condition,$params);

This method is to query a set of data based on conditions, which can be multiple conditions. Put the conditions into the array, and it will also query the first piece of data, such as:
Copy code The code is as follows: findByAttributes(array('username'=>'admin'));
4. $admin=Admin::model()->findBySql($sql,$params);

This method is to query a set of data based on SQL statements. It also queries the first piece of data, such as:
Copy code The code is as follows: findBySql("select *from admin where username=:name",array(':name'=>'admin'));
5. Put together a method to obtain SQL, and query an object based on find

$criteria=new CDbCriteria;
$criteria->select='username'; // only select the 'title' column
$criteria->condition='username=:username';
$criteria->params=array(':username=>'admin');
$post=Post::model()->find($criteria); // $params is not needed

3. Query the number and determine whether the query has results

1. $n=Post::model()->count($condition,$params);

该方法是根据一个条件查询一个集合有多少条记录，返回一个int型数字,如
复制代码 代码如下:count("username=:name",array(":name"=>$username));
2、$n=Post::model()->countBySql($sql,$params);

该方法是根据SQL语句查询一个集合有多少条记录，返回一个int型数字,如
复制代码 代码如下:countBySql("select *from admin where username=:name",array(':name'=>'admin'));
3、$exists=Post::model()->exists($condition,$params);
该方法是根据一个条件查询查询得到的数组有没有数据，如果有数据返回一个true，否则没有找到

四、添加的方法

$admin=new Admin;
$admin->username=$username;
$admin->password=$password;
if($admin->save()>0){
  echo "添加成功";
}else{
  echo "添加失败";
}

五、修改的方法

1、Post::model()->updateAll($attributes,$condition,$params);

$count = Admin::model()->updateAll(array('username'=>'11111','password'=>'11111'),'password=:pass',array(':pass'=>'1111a1'));
if($count>0){
  echo "修改成功";
}else{
  echo "修改失败";
}

2、Post::model()->updateByPk($pk,$attributes,$condition,$params);

$count = Admin::model()->updateByPk(1,array('username'=>'admin','password'=>'admin'));
$count = Admin::model()->updateByPk(array(1,2),array('username'=>'admin','password'=>'admin'),'username=:name',array(':name'=>'admin'));
if($count>0){
  echo "修改成功";
}else{
  echo "修改失败";
}

$pk代表主键，可以是一个也可以是一个集合，$attributes代表是要修改的字段的集合，$condition代表条件，$params传入的值

3、Post::model()->updateCounters($counters,$condition,$params);

$count =Admin::model()->updateCounters(array('status'=>1),'username=:name',array(':name'=>'admin'));
if($count>0){
  echo "修改成功";
}else{
  echo "修改失败";
}

array('status'=>1)代表数据库中的admin表根据条件username='admin'，查询出的所有结果status字段都自加1

六、删除的方法

1、Post::model()->deleteAll($condition,$params);

$count = Admin::model()->deleteAll('username=:name and password=:pass',array(':name'=>'admin',':pass'=>'admin'));
      $id=1,2,3
      deleteAll('id in(".$id.")');删除id为这些的数据
if($count>0){
  echo "删除成功";
}else{
  echo "删除失败";
}

2、Post::model()->deleteByPk($pk,$condition,$params);

$count = Admin::model()->deleteByPk(1);
$count = Admin::model()->deleteByPk(array(1,2),'username=:name',array(':name'=>'admin'));
if($count>0){
  echo "删除成功";
}else{
  echo "删除失败";
}

希望本文所述对大家基于Yii框架的PHP程序设计有所帮助。

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