Php 在mysql中选择相邻行–但使用特定列的字母顺序，而不是ID的数字顺序时

我有一个wordpress安装，带有自定义的post类型，我希望通过mysql找到“previous”和“next”自定义post类型对象

关于如何在使用ID时实现这一点，我已经阅读了很多关于SO的问题/答案。问题是，这些对象中有很多是在不同的时间输入的，因此它们的数字“ID”顺序不一定与它们的字符串post_title顺序对应

例如：

SQL查询：

SELECT ID, post_title 
FROM wp_posts 
WHERE post_type = 'custom_type' 
ORDER BY post_title ASC

给我结果。如果我从上面知道ID，例如b，1，我怎么会发现，当按post_title排序时，相邻的post是7和3？

您可以使用union all执行此操作：

---

如何按CPT中相邻帖子的字母顺序排序。可能比较干燥，但这是其他溶液的1/4

add_action( 'wp_head', 'projectprefix_adjacent_post_equipment_filters' );
/**
 * Sort Adjacent Posts (previous and next) in CPT alphabetically
 * get_previous_post_join, get_next_post_join
 * get_previous_post_where, get_next_post_where
 * get_previous_post_sort, get_next_post_sort
 * Ref: https://wordpress.stackexchange.com/a/73194/64742 
 */
function projectprefix_adjacent_post_equipment_filters() {

    // exit early
    if ( ! is_singular( array( 'registered_cpt' ) ) ) return; 

    
    add_filter( 'get_previous_post_where', 'projectprefix_prev_post_where' );
    
    function projectprefix_prev_post_where( $where ) {
        global $post, $wpdb;
        $where = $wpdb->prepare( "WHERE p.menu_order > '%s' AND p.post_type = 'registered_cpt' AND p.post_status = 'publish'",$post->menu_order );
        return $where;
    }


    add_filter( 'get_next_post_where', 'projectprefix_next_post_where' );
    
    function projectprefix_next_post_where( $where ) {
        global $post, $wpdb;
        $where = $wpdb->prepare( "WHERE p.menu_order < '%s' AND p.post_type = 'registered_cpt' AND p.post_status = 'publish'",$post->menu_order );
        return $where;
    }


    add_filter( 'get_previous_post_sort', 'projectprefix_previous_post_orderby' );
    
    function projectprefix_previous_post_orderby( $orderby ) {
        return "ORDER BY p.menu_order ASC LIMIT 1";
    }
    

    add_filter( 'get_next_post_sort', 'projectprefix_next_post_orderby' );
    
    function projectprefix_next_post_orderby( $orderby ) {
        return "ORDER BY p.menu_order DESC LIMIT 1";
    }

}

---

可能的重复项没有post_日期字段，为什么不能按日期字段排序？@BrianDeMilia原因是我想要基于字母顺序的prev/next，而不是日期。这不太管用，但这个，以及上面的相关问题确实帮助我找到了解决方案，我没有意识到mysql可以使用字符串，所以这个答案的唯一问题是我想按post_标题排序，所以第4行应该是post_标题<。。。而且它工作得很好。

(SELECT ID, post_title 
 FROM wp_posts 
 WHERE post_type = 'custom_type' and
       post_type < (select post_title from wp_posts where post_type = 'custom_type' and id = 1)
 ORDER BY post_title DESC
 LIMIT 1, 1
)
UNION ALL
(SELECT ID, post_title 
 FROM wp_posts 
 WHERE post_type = 'custom_type' and
       post_type > (select post_title from wp_posts where post_type = 'custom_type' and id = 1)
 ORDER BY post_title ASC
 LIMIT 1
)
ORDER BY ID;

add_action( 'wp_head', 'projectprefix_adjacent_post_equipment_filters' );
/**
 * Sort Adjacent Posts (previous and next) in CPT alphabetically
 * get_previous_post_join, get_next_post_join
 * get_previous_post_where, get_next_post_where
 * get_previous_post_sort, get_next_post_sort
 * Ref: https://wordpress.stackexchange.com/a/73194/64742 
 */
function projectprefix_adjacent_post_equipment_filters() {

    // exit early
    if ( ! is_singular( array( 'registered_cpt' ) ) ) return; 

    
    add_filter( 'get_previous_post_where', 'projectprefix_prev_post_where' );
    
    function projectprefix_prev_post_where( $where ) {
        global $post, $wpdb;
        $where = $wpdb->prepare( "WHERE p.menu_order > '%s' AND p.post_type = 'registered_cpt' AND p.post_status = 'publish'",$post->menu_order );
        return $where;
    }


    add_filter( 'get_next_post_where', 'projectprefix_next_post_where' );
    
    function projectprefix_next_post_where( $where ) {
        global $post, $wpdb;
        $where = $wpdb->prepare( "WHERE p.menu_order < '%s' AND p.post_type = 'registered_cpt' AND p.post_status = 'publish'",$post->menu_order );
        return $where;
    }


    add_filter( 'get_previous_post_sort', 'projectprefix_previous_post_orderby' );
    
    function projectprefix_previous_post_orderby( $orderby ) {
        return "ORDER BY p.menu_order ASC LIMIT 1";
    }
    

    add_filter( 'get_next_post_sort', 'projectprefix_next_post_orderby' );
    
    function projectprefix_next_post_orderby( $orderby ) {
        return "ORDER BY p.menu_order DESC LIMIT 1";
    }

}