“'condition'=>'project_id =：projectId'，”是什么？“：”的含义是什么？

Question

I don't know What is the“'condition'=>'project_id=:projectId',”？what is the meaning of “：”？ In another word why we should put the “：” in front of the projectId. the code is as below.

public function actionIndex()
    {
        $dataProvider=new CActiveDataProvider('Issue',array(
            'criteria'=>array(
                'condition'=>'project_id=:projectId',
                'params'=>array(':projectId'=>$this->_project->id),
            ),
        ));

Answer 1

The way I understand your code snippet, this has to do with escaping query parameters / prepared SQL statements. This prevents SQL injection. In your example, :projectId in condition is another way of saying "Please replace this :projectId with the escaped value of :projectId ( $this-_project->id ) from params when executing this query".