我只知道最简单的SQL,所以请把我当成一个完整的菜鸟!
我有一个有很多行的表,但有些可以通过id配对,我想要合并这些行的返回数组。
post_id # meta_name # meta_value #
======================================
1 # bar # 44 #
1 # foo # on #
2 # bar # 1 #
2 # foo # on #
3 # bar # 1 #
3 # foo # off #
作为缩小版本,想象一下我的表格的上方,我的目标是返回2个结果
1 # foo # bar # 44 # on
2 # foo # bar # 1 # on
基于ids相关且c2的值为'on'
我的尝试是从一些阅读中得到的,但没有得到任何结果
SELECT
t1.post_id, t2.post_id, t1.meta_name, t2.meta_name, t1.meta_value, t2.meta_value
FROM
`ecom_page_meta` t1
JOIN
`ecom_page_meta` t2
ON
t1.post_id = t2.post_id
WHERE
t1.meta_name = 'featured-products'
AND
t1.meta_value = 'on'
任何帮助都会非常感激
**编辑**
由于下面的答案,我认为我只是发布下面很好用的语法:
SELECT L.post_id, L.meta_name, R.meta_name, L.meta_value, R.meta_value
FROM `ecom_page_meta` L
INNER JOIN ecom_page_meta R
ON L.post_id = R.post_id
AND L.meta_name = 'featured-products-order'
AND R.meta_value = 'on'
WHERE R.meta_name = 'featured-products'
ORDER BY L.meta_value
DESC
再次感谢。
答案 0 :(得分:3)
创建测试数据:
SQL> create table ecom_page_meta (post_id number not null
2 , meta_name varchar2(15) not null
3 , meta_value varchar2(15) not null);
Table created.
SQL> insert into ecom_page_meta values (1, 'bar', '44');
1 row created.
SQL> insert into ecom_page_meta values (1, 'foo', 'on');
1 row created.
SQL> insert into ecom_page_meta values (2, 'bar', '1');
1 row created.
SQL> insert into ecom_page_meta values (2, 'foo', 'on');
1 row created.
SQL> insert into ecom_page_meta values (3, 'bar', '1');
1 row created.
SQL> insert into ecom_page_meta values (3, 'foo', 'off');
1 row created.
SQL> commit;
Commit complete.
查询以给出与OP样本匹配的结果:
SQL> select L.post_id, L.meta_name, R.meta_name, L.meta_value, R.meta_value
2 from ecom_page_meta L
3 inner join ecom_page_meta R
4 on L.post_id = R.post_id
5 and L.meta_value <> 'on'
6 and R.meta_value = 'on'
7 where L.meta_name = 'bar';
POST_ID META_NAME META_NAME META_VALUE META_VALUE
---------- --------------- --------------- --------------- ---------------
1 bar foo 44 on
2 bar foo 1 on
我仍然不知道WHERE t1.meta_name = 'featured-products'
对任何事情做了什么,因为没有样本数据包含字符串'featured-products'的t1.meta_name。