Three ways to operate the database in yii

1. PDO method of executing native SQL

The code is as follows:

$sql = "";//原生态sql语句 
xx::model()->dbConnection->createCommand($sql)->execute();

2. Active Record Method

(1) New method

The code is as follows:

$post=new Post; 
$post->title='sample post'; 
$post->content='post body content'; 
$post->save();

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(2) Criteria method

You can also use $condition to specify more complex query conditions. Instead of using a string, we can make $condition an instance of CDbCriteria, which allows us to specify conditions that are not limited to WHERE.

The code is as follows:

$criteria=new CDbCriteria; 
$criteria->select='title';  // 只选择 'title' 列 
$criteria->condition='postID=:postID'; 
$criteria->params=array(':postID'=>10); 
$post=Post::model()->find($criteria);

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), 
));

When a query condition is about matching several columns by a specified value, we can Use findByAttributes(). We make the $attributes parameter an array of values ​​indexed by column names.

In some frameworks, this task can be achieved by calling a method like findByNameAndTitle. Although this approach seems tempting, it often causes confusion, conflicts, and issues such as case-sensitivity of column names.

3. Query Builder method

The code is as follows:

$user = Yii::app()->db->createCommand() 
    ->select('id, username, profile') 
    ->from('tbl_user u') 
    ->join('tbl_profile p', 'u.id=p.user_id') 
    ->where('id=:id', array(':id'=>$id)) 
    ->queryRow();

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