How can I combine two SQL queries using INNER JOIN? - php

Question

I have 2 SQL queries as below:
$results2 = $wpdb->get_results("SELECT * FROM `wp_posts` WHERE id IN (".implode(",", $product_ids).")");
$getprice = $wpdb->get_results("SELECT * FROM `wp_postmeta` WHERE meta_key='_regular_price' AND post_id IN (".implode(",", $product_ids).")");
I have combined them as below query:
$yeni = $wpdb->get_results("SELECT wp_posts.id, wp_posts.post_title, wp_postmeta.meta_value
FROM wp_posts
INNER JOIN wp_postmeta ON wp_posts.id = wp_postmeta.post_id
WHERE meta_key = '_regular_price'
WHERE wp_posts.id IN (".implode(",", $product_ids).")");
After combining the queries, it's giving an empty result. I can't find the issue with the updated query.

Answer 1

Try this sql.
I have replace this WHERE meta_key = '_regular_price'
$yeni = $wpdb->get_results("SELECT wp_posts.id, wp_posts.post_title, wp_postmeta.meta_value FROM wp_posts INNER JOIN wp_postmeta ON wp_posts.id = wp_postmeta.post_id WHERE wp_posts.id IN (".implode(",", $product_ids).") and wp_postmeta.meta_key = '_regular_price'");

Answer 2

I don't understand why you don't use the native Wordpress features via OOP procedure.
Your simple query, it can be translated like this:
<?php
$loop = new WP_Query(
array(
'post_type' => 'page', // post type: page, post, attachment etc..
'post__in' => $productIds, // array[]
)
);
// after that, you can use a standard wordpress loop
if($loop->have_posts()) {
while($loop->have_posts()) {
: $loop->the_post();
the_title();
print "<br>";
// access to meta key _regular_price
print get_post_meta(get_the_ID(), '_regular_price', true);
}
}
This is the right way.
Cheers
Class reference here: https://developer.wordpress.org/reference/classes/wp_query/