Deleting data from multiple table - mysql

Question

I am trying to delete data from two different table at the same time but it seems like the query is not deleting data. First I will check either user have posted any blog and delete from user and blog if the query is true.
Here is my controller :
public function delete(){
if(isset($_SESSION['userLogId'])){
$selectedId = $this->uri->segment(3);
// getting the current image and unlink it if image exist
$currentImage = $this->User_account_model->currentImage('student', $selectedId);
if($currentImage != null){
$_SESSION['current_image'] = $currentImage->photo;
}
$isDeleted = $this->User_account_model->deleteUser($selectedId);
if($isDeleted == true){
if(isset($_SESSION['current_image']) && !empty($_SESSION['current_image'])){
unlink($_SERVER['DOCUMENT_ROOT']."/uploadfiles/users/student-img/".$_SESSION['current_image']);
unset($_SESSION['current_image']);
}
echo '<script>';
echo 'alert("User removed successfully.");';
echo 'window.location.href = "'.base_url('account/view-user/').'";';
echo '</script>';
} else {
echo '<script>';
echo 'alert("Error while removing. Deleting user unable to processed.");';
echo 'window.location.href = "'.base_url('account/view-user/').'";';
echo '</script>';
}
}
}
My model function to delete user :
function deleteUser($selectedId){
// first check either user have posted blog
$this->db->select('user_id');
$this->db->from('blog_content');
$this->db->where('user_id', $selectedId);
$query = $this->db->get();
$r = $query->row();
if(!empty($r)){
$this->db->delete('users_student, blog_content');
$this->db->from('users_student, blog_content');
$this->db->where('blog_content.user_id = users_student.id');
$this->db->where('users_student.id',$selectedId);
if($this->db->affected_rows()){
return true;
} else { return false; }
} else {
$this->db->delete('users_student');
$this->db->where('id',$selectedId);
if($this->db->affected_rows()){
return true;
} else { return false; }
}
}

Answer 1

In your deleteUser function, replace this code:
$this->db->delete('users_student, blog_content');
$this->db->from('users_student, blog_content');
$this->db->where('blog_content.user_id = users_student.id');
$this->db->where('users_student.id',$selectedId);
with this:
$this->db->delete('blog_content', array('user_id' => $selectedId));
$this->db->delete('users_student', array('id' => $selectedId));

Answer 2

I have solved my issue. It is the Codeigniter query format to delete.
Note : In Codeigniter delete query, specify WHERE first before DELETE
function deleteUser($selectedId){
// first check either user have posted blog
$this->db->select('user_id');
$this->db->from('blog_content');
$this->db->where('user_id', $selectedId);
$query = $this->db->get();
$r = $query->row();
if(!empty($r)){
// delete from blog first
$this->db->where('user_id',$selectedId);
$this->db->delete('blog_content');
if($this->db->affected_rows()){
// then delete from user
$this->db->where('id',$selectedId);
$this->db->delete('users_student');
if($this->db->affected_rows()){
return true;
} else { return false; }
}
} else {
$this->db->where('id',$selectedId);
$this->db->delete('users_student');
if($this->db->affected_rows()){
return true;
} else { return false; }
}
}