Best way to prevent post duplication when using multiple loops

Question

I have the following loops on a page on my website.

Whats the best way to adapt the code below to stop the post in my first loop, being repeated in the second?

    <?php query_posts('showposts=1&post_type=post'); ?>

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<div id="latestpost" <?php

    if ( $thumbnail_id = get_post_thumbnail_id() ) {
        if ( $image_src = wp_get_attachment_image_src( $thumbnail_id, 'normal-bg' ) )
            printf( ' style="background-image: url(%s);"', $image_src[0] );     
    }

?>>

    <article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
                    <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>">



    <h2><?php the_title() ;?></h2>      
    <div class="summary" style="color:#fff;">
        <?php the_excerpt(); ?>
        </div>
    <!-- <?php the_post_thumbnail(); ?> -->
<?php endwhile; else: ?>

    <p>Sorry, there are no posts to display</p>
                    </a><!-- permalink -->
<?php endif; ?>
    </article>
</div><!-- latest post -->

<?php wp_reset_query(); ?>


<div id="postlist">

<h2>Personal finances</h2>

<?php query_posts('showposts=3&post_type=post&category_name=Personal');
 ?>

<?php if ( have_posts() ) : while ( have_posts() ) : the_post();  ?>

    <!-- article -->
    <article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
        <!-- post title -->
        <div class="post-thumbnail">
        <!-- post thumbnail -->
        <?php if ( has_post_thumbnail()) : // Check if thumbnail exists ?>
            <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>">
                <?php the_post_thumbnail(array(120,120)); // Declare pixel size you need inside the array ?>
            </a>
        <?php endif; ?>
        <!-- /post thumbnail -->
        </div>

        <h3 class="postlist-article-header">
            <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a>
        </h3>
        <!-- /post title -->


    </article>
    <!-- /article -->

<?php endwhile; ?>

<?php else: ?>

    <!-- article -->
    <article>
        <h2><?php _e( 'Sorry, nothing to display.', 'html5blank' ); ?></h2>
    </article>
    <!-- /article -->

<?php endif; ?>

<?php wp_reset_query(); ?>

Answer 1

You can gather the post id(s) from the first loop in an array and then use post__not_in arg in the second loop.

$exclude = array();
if ( have_posts() ) : while ( have_posts() ) : the_post();
//first loop
$exclude[] = get_the_ID();
...


//second loop
$second_loop_args = array(
    'showposts' => 3,
    'post_type' => 'post',
    'category_name' => 'Personal', //should make sure you're using category slug here
    'post__not_in' => $exclude //this arg needs to be an array, hence moving from string to array format for query_post args
);
query_posts($second_loop_args);
....

**I will say though, that you should reconsider using new WP_Query() for your loops instead of query_posts as detailed here: https://codex.wordpress.org/Class_Reference/WP_Query

It's basicaly the same, but instead of using query_posts, you just assign a variable your new WP_Query class and loop through it.