Esta pergunta já tem uma resposta aqui:

Visão

$("#submit").on('click',function(e){
    e.preventDefault();
    product_name = $("#product_name").val();
    category = $("#category").val();
    var formData = new FormData();
    $.each($("#product_image"), function (i, obj) {
        $.each(obj.files, function (j, file) {                    
            formData.append('product_image[' + i + ']', file);
        });
    });
    formData.append('product_name', product_name);
    formData.append('category', category);
    $.ajax({
        type:"POST",
        data:formData,
        processData: false,
        contentType: false,
        url:"<?php echo base_url(); ?>admin/products",
        success:function(data){
            alert(data);
        }
    });
});

Controlador

public function products()
{
    $dataInfo = array();
    $files = $_FILES;
    $cpt = count($_FILES['product_image']['name']);
    for($i=0; $i<$cpt; $i++)
    {           
        $_FILES['product_image']['name']= $files['product_image']['name'][$i];
        $_FILES['product_image']['type']= $files['product_image']['type'][$i];
        $_FILES['product_image']['tmp_name']= $files['product_image']['tmp_name'][$i];
        $_FILES['product_image']['error']= $files['product_image']['error'][$i];
        $_FILES['product_image']['size']= $files['product_image']['size'][$i];    

        $this->upload->initialize($this->set_upload_options());
        $this->upload->do_upload();
        $dataInfo[] = $this->upload->data();
    }

    $data = array(

            'product_name' => $this->input->post('product_name'),
            'category' => $this->input->post('category'),
            'product_image' => implode(",",array_column($dataInfo, 'product_image'))
        );
    $sql = $this->db->insert('add_product',$data);
    if($sql == true)
    {
        echo 'New Product Added';
    }
    else
    {
        echo 'Unable to Proceed!';
    }
}

private function set_upload_options()
{   
    $config = array();
    $config['upload_path'] = ''.base_url().'resource/product/';
    $config['allowed_types'] = 'gif|jpg|png';
    $config['max_size']      = '0';
    $config['overwrite']     = FALSE;
    return $config;
}

Tenho três campos de entrada, ou seja,product_name,category and product_image. Agora, quero mover várias imagens e inserirproduct_image nome separado por vírgula (,), por exemploimg1.jpg,img2.jpg,img3.jpg Curtiu isso. Agora, quando eu alerta responder, não mostra nada. Então, como posso resolver? Por favor me ajude

demonstração de saída esperada do mysql como

product_name    category    product_images
============    ========    ==============
men t-shirt     MEN         img1.jp,img2.jpg,img3.jpg
kids t-shirt    kids        img1.jp,img2.jpg,img3.jpg