How to get orders that contains a product by date?

The issue here is that you’re trying to match the post_date exactly with $order_date. However, post_date is a datetime field and includes the time as well, so it’s unlikely to match exactly with a date string like ‘2023-02-28’.

If you want to get orders by month, you can use the MySQL MONTH() and YEAR() functions to extract the month and year from the post_date and compare it with the month and year of $order_date. Here’s how you can modify your function:

function get_orders_by_product($product_id, $order_date) {
      
    global $wpdb;
    $order_status = ['wc-completed'];

    // Extract the month and year from $order_date
    $order_month = date('m', strtotime($order_date));
    $order_year = date('Y', strtotime($order_date));

    $results = $wpdb->get_col("
        SELECT order_items.order_id
        FROM {$wpdb->prefix}woocommerce_order_items as order_items
        LEFT JOIN {$wpdb->prefix}woocommerce_order_itemmeta as order_item_meta ON order_items.order_item_id = order_item_meta.order_item_id
        LEFT JOIN {$wpdb->posts} AS posts ON order_items.order_id = posts.ID
        WHERE posts.post_type="shop_order"
        AND posts.post_status IN ( '" . implode( "','", $order_status ) . "' )
        AND MONTH(posts.post_date) = $order_month
        AND YEAR(posts.post_date) = $order_year
        AND order_items.order_item_type="line_item"
        AND order_item_meta.meta_key = '_product_id'
        AND order_item_meta.meta_value="".$product_id.""
        ORDER BY order_items.order_id DESC");
    return $results;
}
get_orders_by_product(19361,'2023-02-28');