codeigniter check if record exists

I have 3 tables,category w/c consist of (category_id,name),ingredient w/c consist of (ingredient_id,name) and category_ingredient w/c consist of(ingredient_id,category_id). now i want to add a condition in the category_ingredient that can check if an ingredient and category is the same then i cant add that certain ingredient. can u guys help me?please

table

this is my code:

VIEW: add_ingredients.php

  <?php echo form_open('dashboard/uploadIngredients', 'class="form-horizontal" enctype="multipart/form-data"'); ?>
    <div class="form-group">
        <div class="col-sm-10">

            <select class="form-control" name="ingredient_category">

                <option selected disabled>Select Ingredient Category</option>
            <option value="All">All</option>
            <?php foreach($this->products_model->getCategory() as $row): ?>
                <option value="<?php echo $row->category_id ?>"><?php echo $row->name; ?></option>
            <?php endforeach; ?>
            </select>

        </div>
    </div>
    <div class="form-group">
        <div class="col-sm-10">
            <textarea class="form-control" name="ingredients" rows="5" placeholder="Ingredients (EX. onion, oil, pasta)"></textarea> 
        </div>
    </div>

    <div class='form-group'>
        <div class="col-sm-10">
            <button class="btn btn-lg btn-positive" type="submit"><i class="glyphicon glyphicon-ok"></i> Save Ingredient</button>
        </div>
    </div>
<?php echo form_close(); ?>

CONTROLLER: dashboard.php

 private function checkExist($param1,$param2){
    $res=$this->recipick->findExist($param1,$param2);
    if($res>0){
    return true;
    }else{
    return false;
    }
    }

  public function uploadIngredients()

{

$this -> form_validation -> set_rules("name", "Name", "required|xss_clean|is_unique[recipick.ingredient_id]");
foreach(explode(',', $this->input->post('ingredients')) as $key => $value)
{
    $saveData[] = array('ingredient_id' => null,
                        'name'  => trim($value)
    );  
}

$ingredient_id = $this->products_model->saveIngredients($saveData);
foreach (explode(',', $this->input->post('ingredient_category')) as $key => $value)
{
    foreach ( $ingredient_id as $key => $str ){
            $joinData[] = array(
                                'ingredient_id'     => $str,
                                'category_id'       => intval($value)
            );
    }

    $this->products_model->saveCategoryIngredients($joinData);

    redirect('dashboard/add_ingredients');
    }


}

MODEL:products_model.php

  public function saveIngredients($data) {
    foreach($data as $row => $value)
            {
                $this->db->insert('ingredient', $value);
                $insert_id[] = $this->db->insert_id();  
            }

            return $insert_id;
    }

  public function saveCategoryIngredients($data)
    {

               foreach($data as $row => $value)
            {
                $this->db->insert('category_ingredient', $value);
                $insert_id[] = $this->db->insert_id();  
            }

            return $insert_id;
    }
  public function findExist($param1,$param2)
   {
    $query=$this->db->query("select * category_ingredient where ingredient_id='".$param1."' and category_id='".$param2."'");return count($query);}

but i can still add same same ingredient with same category