我是MySQL的新手，我正在尝试编写一个非常高级的查询。但是嘿！边做边学边学计算器！
我可能会在不太高级的查询/查询中获取所有数据，并使用PHP对数据进行排序。但我认为它可以直接在查询中完成。
以下是我的代码。如果您不理解，请询问问题，我会尝试更好地解释。如果您发现任何错误，请帮我纠正代码。
该代码将用于在我的wordpress页面上显示不同的字段。不同的fildes将有不同的类别，例如。 sidebar-blog，sidebar-page，highlight-blog，highlight-page。它几乎像常规帖子一样工作。
以下是Wordpress的数据库结构：
问题：
我如何加入表格：wp_posts，wp_term_relationships，wp_term_taxonomy，wp_terms和wp_postmeta？
进行高级查询或使用PHP处理if / else函数是不错的做法？
<?php
$id = $post->ID; // Gets the ID of current page
$query = "
SELECT wp_posts.post_content, wp_posts.ID, wp_terms.slug # Data from two different tables
FROM wp_posts
# Cant figure out how to join the tables
INNER JOIN wp_postmeta
ON wp_posts.ID = wp_postmeta.post_id
INNER JOIN wp_term_relationships
ON wp_posts.ID = wp_term_relationships.object_id
INNER JOIN wp_term_taxonomy
ON wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id
INNER JOIN wp_terms
ON wp_term_taxonomy.term_id = wp_terms.term_id
WHERE
wp_posts.post_type = 'my-own-post-type' # Only get specific post-type
AND
wp_posts.post_status = 'publish' # Only get published posts
AND
# START - Only get categories specified here
(
wp_terms.slug = 'category-1'
OR
wp_terms.slug = 'category-2'
OR
wp_terms.slug = 'category-3'
OR
wp_terms.slug = 'category-4'
OR
wp_terms.slug = 'category-5'
)
# END - Only get categories specified here
AND
# I want to be able to include or exclude specific pages, even if category is the right one
# Exlude = Don't get data if current page ID is found (ID of current page will be checked in meta_value using %,$id,%)
# Include means: If include value is specifyed, then get data ONLY if ID is found (ID of current page will be checked in meta_value using %,$id,%)
# If not exclude and include are set, it should get the data
# START - Include exclude
(
# exclude is set, so check if page id match anywhere. If it IS found it it should not get the data, otherwise YES
wp_postmeta.meta_key = 'exclude' AND wp_postmeta.meta_value <> '%,$id,%'
OR
# include is set, so check if page id match anywhere. If it IS NOT found it it should not get the data, otherwise YES
wp_postmeta.meta_key = 'include' AND wp_postmeta.meta_value = '%,$id,%'
OR
# If exclude and include aren't set it should get the data
wp_postmeta.meta_key <> 'exkludera' AND wp_postmeta.meta_key <> 'include'
)
# END - Include exclude
";
$result = mysql_query($query);
while($row = mysql_fetch_array($result))
{
// collect all fields in category 1 (eg. sidebar)
if($row['slug'] == 'category-1'){
$all_fields_from_category_1 = $all_fields_from_category_1.'
<div id="field-sidebar">
'.$row['post_content'].'
</div>
';}
// collect all fields in category 1 (eg. highlight)
if($row['slug'] == 'category-2'){
$all_fields_from_category_2 = $all_fields_from_category_2.'
<div id="field-highlight">
'.$row['post_content'].'
</div>
';}
} // end while
// sidebar
echo '<div id="container-sidebar">'.
$all_fields_from_category_1.
'</div>';
// highlight
echo '<div id="container-highlight">'.
$all_fields_from_category_1.
'</div>';
?>
新版本，新问题：
SELECT DISTINCT wp_posts.post_content, wp_posts.ID, wp_terms.slug
FROM wp_posts
JOIN wp_postmeta ON wp_posts.ID = wp_postmeta.post_id
JOIN wp_term_relationships ON wp_posts.ID = wp_term_relationships.object_id
JOIN wp_term_taxonomy ON wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id
JOIN wp_terms ON wp_term_taxonomy.term_id = wp_terms.term_id
WHERE wp_posts.post_type = 'my-own-fields'
AND wp_posts.post_status = 'publish'
AND wp_terms.slug IN
('field1', 'field2', 'field3', 'field4', 'field5', 'field6')
AND
(
wp_postmeta.meta_key = 'exlude' AND wp_postmeta.meta_value <> '$id'
OR wp_postmeta.meta_key = 'include' AND wp_postmeta.meta_value = '$id'
OR wp_postmeta.meta_key <> 'exlude' AND wp_postmeta.meta_value <> 'include' #LAST ROW
)
即使设置了exclude或include，“#LAST ROW”也会返回数据。因为它与表wp_postmeta中的其他两行匹配。
表wp_postmeta的示例：
meta_id post_id meta_key meta_value
1 30 include 18
2 30 _edit_lock 1322225789:1
3 30 _edit_last 1
如果为post_id找不到meta_key的排除或排除，我想返回数据......
当我想要返回数据时的示例性事件：
meta_id post_id meta_key meta_value
2 30 _edit_lock 1322225789:1
3 30 _edit_last 1
我知道如何解决这个问题？ 声明如下：如果没有找到包含exclude或include的行用于当前id。返回数据。
更多例子：
post_id是30。
如果senario是：
meta_id post_id meta_key meta_value
1 30 include 18
2 30 _edit_lock 1322225789:1
3 30 _edit_last 1
然后我想回到wp_posts.post_content，wp_posts.ID和wp_terms.slug，因为$ id是18。
如果senario是：
meta_id post_id meta_key meta_value
1 30 exclude 18
2 30 _edit_lock 1322225789:1
3 30 _edit_last 1
然后我想回到wp_posts.post_content，wp_posts.ID和wp_terms.slug，因为$ id不是18。
如果senario是：
meta_id post_id meta_key meta_value
2 30 _edit_lock 1322225789:1
3 30 _edit_last 1
然后我想找回wp_posts.post_content，wp_posts.ID和wp_terms.slug。
答案 0 :(得分：6)
您的联接已正确完成。删除你的评论和额外的行时，你会发现查询并不是那么复杂。我做的唯一真正的改变是将wp_terms.slug的OR列表更改为IN语句。这样做只是为了减少代码重复，清理外观，而不是改变功能。
SELECT p.post_content, p.ID, t.slug
FROM wp_posts AS p
INNER JOIN wp_postmeta AS pm ON p.ID = pm.post_id
INNER JOIN wp_term_relationships AS tr ON p.ID = tr.object_id
INNER JOIN wp_term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id
INNER JOIN wp_terms AS t ON tt.term_id = t.term_id
WHERE p.post_type = 'my-own-post-type'
AND p.post_status = 'publish'
AND t.slug IN
('category-1', 'category-2', 'category-3', 'category-4', 'category-5')
AND
(
( pm.meta_key = 'exclude' AND pm.meta_value <> '$id' )
OR ( pm.meta_key = 'include' AND pm.meta_value = '$id' )
OR ( pm.meta_key <> 'exclude' AND pm.meta_value <> 'include' )
)