如何防止Code Igniter中的SQL注入？

Question

My program failed the security scannning for sql injection. The following is one of my function to insert data into db.. Please advice how should I modify my code to prevent SQL injection. Thanks in advance.

public function set_timeline() {
    $this->load->helper('url');
    $this->load->helper('form');
    $data = array(
        'fiid' => $this->input->post('fiid'),
        'project_id' => $this->input->post('project_id'),
        'testing' => $this->input->post('testing'),
        'start_date' => $this->input->post('start_date'),
        'end_date' => $this->input->post('end_date'),
        'description' => $this->input->post('description'),
        'project_progress' => $this->input->post('project_progress'),
        'tester' => $this->input->post('tester'),
        'status' => $this->input->post('status')
    );

    $this->db->insert('timeline',$data);

    if ($this->db->affected_rows() > 0) {
        echo '<script>alert("Timeline Added Successfully"); window.history.back(); </script>';
    }
    else {  
        echo '<script>alert("Timeline already exist!"); window.history.back();</script>';
    }                       
}