<?php

function insert_currency()
{
    global $wpdb;
    $table = $wpdb->prefix . 'currency';

    $wpdb->insert( $table , array (
        'DATE' => '2018-01-01',
        'NAME' => 'usd',
        'CURRENCY' => '20.2265'
    ) );

    return "test";
}

function get_bnm_data()
{
    insert_currency();
}

add_shortcode( 'currency_insert','insert_currency' );