Question

我试图从表格term_relationships中选择不同的（tr.item_id）。如果它与许多标签相关，我想避免两次列出帖子。

有人能指出我正确的方向吗？

查询：

tag_inject = "tr.taxonomy_id = 94 or tr.taxonomy_id = 92 or tr.taxonomy_id = 93"

SELECT * FROM term_relationships tr" + _
" INNER JOIN term_taxonomy tax ON tr.taxonomy_id = tax.taxonomy_id" + _
" INNER JOIN post po ON tr.item_id = po.post_id" + _
" where tr.cpa_id = " & cpa_id & " and (" & tag_inject & ")" + _
" and po.cpa_id = " & cpa_id & " and po.post_status = 1" + _
" order by po.post_start_date desc limit " & amount_1

我在这里回答，因为评论字段很小，我不想等待6个小时

谢谢你们，

我试图在一个查询中完成整个过程，但是当我需要item_id不同时，我不认为这是可能的吗？

因此，在获得不同的项目列表后，我决定使用子查询获取帖子数据。

有点像这样：

sql_tags = "SELECT distinct tr.item_id" + _
" FROM term_relationships tr" + _
" INNER JOIN term_taxonomy tax ON tr.taxonomy_id = tax.taxonomy_id" + _
" INNER JOIN post po ON tr.item_id = po.post_id" + _
" where tr.cpa_id = " & clng(cpa_id) & " and (" & tag_inject & ")" + _
" and po.cpa_id = " & clng(cpa_id) & " and po.post_status = 1" + _
" order by po.post_start_date desc limit " & clng(content_amount_1)
set rs_plist = conn.execute(sql_tags)

然后..

while not rs_plist.eof 

get_item_id = rs_plist("item_id")

sql = "select rec_id, post_id, post_title, post_line_desc, post_image_1, post_image_1_width from " & app_database & ".post" + _
" where cpa_id = " & clng(cpa_id) & " and post_id = " & get_item_id
set rs_post = conn.execute(sql)

..等等..

是否有更好的选择，或者这是否可以做到？

Answer 1

用于选择不同记录的Sql查询。如果您希望输出仅作为表term_relationships中的不同term_id，您可以编写以下查询

SELECT DISTINCT term_id FROM term_relationships

或

SELECT term_id FROM term_relationships GROUP BY term_id

Answer 2

您应指定要检索的字段列表，不能将DISTINCT关键字与*一起使用。

你应该使用这样的东西来获得唯一的post_id

tag_inject = "tr.taxonomy_id = 94 or tr.taxonomy_id = 92 or tr.taxonomy_id = 93"

SELECT DISTINCT po.post_id FROM term_relationships tr" + _
" INNER JOIN term_taxonomy tax ON tr.taxonomy_id = tax.taxonomy_id" + _
" INNER JOIN post po ON tr.item_id = po.post_id" + _
" where tr.cpa_id = " & cpa_id & " and (" & tag_inject & ")" + _
" and po.cpa_id = " & cpa_id & " and po.post_status = 1" + _
" order by po.post_start_date desc limit " & amount_1

Answer 3

使用您的字段名称更具体 - 使用*在技术上是不好的做法。为此，您需要删除指定标记名称的字段，并仅将其包含在WHERE子句中。那样DISTINCT实际上会有效。

在JOIN之后选择DISTINCT值（asp经典）

我在这里回答，因为评论字段很小，我不想等待6个小时

3 个答案: