Argument 2:cannot convert from store.sqlconnection to string

private bool IfProductsExists(Sqlconnection con, string productCode)
{
        SqlDataAdapter sda = new SqlDataAdapter("Select 1 From [Store] WHERE [ProductCode]='" + productCode + "'", con);
        DataTable dt = new DataTable();
        sda.Fill(dt);

        if (dt.Rows.Count > 0)
            return true;
        else
            return false;
}