sql_attr_multi在sphinx可以用来检索有层级关系的数据，效率相当高，如，在数据库中用一个4层的分类，分类下对应着不用的文章，现在需要做一个文章列表，要求，选择第一级分类时属于它的子分类的文章也要显示出来，就可以用下面的方法建索引sql_query= \
SELECT di.company_document_id as id,di.company_document_id, \
di.title as title_attr, di.content as content_attr, \
di.sort, di.weixin_company_id,\
di.is_show,\
di.mod_time,\
dc.category_id, dc.document_type, \
CONCAT(IF(dc.`category_id` is NULL,0,dc.`category_id`),',',IF(dc2.`category_id` is NULL,0,dc2.`category_id`),',',IF(dc3.`category_id` is NULL,0,dc3.`category_id`),',',IF(dc4.`category_id` is NULL,0,dc4.`category_id`)) AS category_ids \
FROM test_company_document di \
LEFT JOIN crm_company_document_category dc ON dc.category_id = di.category_id \
LEFT JOIN test_company_document_category dc2 ON dc.parent_id = dc2.category_id \
LEFT JOIN test_company_document_category dc3 ON dc2.parent_id = dc3.category_id \
LEFT JOIN test_company_document_category dc4 ON dc3.parent_id = dc4.category_id \
WHERE di.is_show =1 AND di.is_delete = 0 \
AND di.company_document_id>=$start AND di.company_document_id<=$end
sql_query_range = SELECT MIN(company_document_id),MAX(company_document_id) FROM test_company_document
sql_range_step = 1000
然后用下面的方法建立sql_attr_multi属性字段：
sql_attr_multi = uint category_ids from field category_ids
生成索引后，表中的数据如下：category_ids...
0,1,2,3...
0,1...
本文原创于phpsir的新浪博客 (phpsir的发现与总结 http://blog.sina.com.cn/phpsir)，未经本人允许禁止转载。
即可用：filter=category_ids,1的方式检索在不同层级分类下的文章。
另外，也可以用下面的语法建立sql_attr_multi字段：# sql_attr_multi = uint atags from ranged-query; \
# SELECT d.company_document_id,da.category_name FROM test_company_document_category da \
# INNER JOIN test_company_document d ON d.category_id = da.category_id \
# WHERE d.company_document_id>=$start AND d.company_document_id<=$end ORDER BY d.company_document_id ASC;\
# SELECT MIN(company_document_id),MAX(company_document_id) FROM test_company_document;