按id获取数据

Question

问题

我有两个不同的插件表，我想通过sql获取它们的值。问题是id，我找不到可以检索数据的连接。

表1 (bdt_mappress_posts)

postid =2和mapid =3

表2 (bdt_mappress_maps)

mapid =3和obj = json

<? $postid = get_the_ID(); 
$results = $GLOBALS['wpdb']->get_results( 'SELECT obj FROM bdt_mappress_maps INNER JOIN bdt_mappress_posts WHERE bdt_mappress_maps.mapid = bdt_mappress_posts AND   bdt_mappress_posts.postid ='.$postid); print_r($results);
 ?>

$postid返回帖子的id。sql返回空值，我知道sql，但不是很强。如果有人能帮助我或给我相关的帖子，我可以找到答案。事前谢谢！

Answer 1

假设这两个表都通过mapid相关，那么您应该使用带有on条件的连接

$results = $GLOBALS['wpdb']->get_results( 'SELECT mapid 
           FROM bdt_mappress_maps 
           INNER JOIN bdt_mappress_posts 
              on (bdt_mappress_maps.mapid = bdt_mappress_posts
                   AND   bdt_mappress_posts.id ='.$postid));

Answer 2

<? $postid = get_the_ID(); 
$results = $GLOBALS['wpdb']->get_results( 'SELECT obj FROM bdt_mappress_posts INNER JOIN bdt_mappress_maps WHERE bdt_mappress_posts.mapid = bdt_mappress_maps.mapid AND   bdt_mappress_posts.postid ='.$postid); print_r($results);
?>

解决问题

这应该只会改变左边sql规则的位置