创建将 4 个元组汇总为一个的 VIEW

Posted 2023-02-26

【中文标题】创建将 4 个元组汇总为一个的 VIEW

【英文标题】：Create VIEW that summarizes 4 tuples in one

【发布时间】：2019-10-28 14:40:04

【问题描述】：

我想创建一个重新格式化我的数据的 SQL VIEW

那是我创建的表格。由于端口需要是唯一的，我将它们放在一列中：

MariaDB [admindb]> select * from table_tennant;
+-------+----------+--------------+----------------+
| port  | protocol | tennant_name | tennant_domain |
+-------+----------+--------------+----------------+
| 10000 | https    | test         | test.test.de   |
| 10001 | smtp     | test         | test.test.de   |
| 10002 | mgmt     | test         | test.test.de   |
| 10003 | solr     | test         | test.test.de   |
| 10010 | https    | test2        | test2.test.de  |
| 10011 | smtp     | test2        | test2.test.de  |
| 10012 | mgmt     | test2        | test2.test.de  |
| 10013 | solr     | test2        | test2.test.de  |
+-------+----------+--------------+----------------+

每个租户的 4 行应该显示为一个，像这样

+----------------+--------------+------------+-----------+-----------+-----------+
| tennant_domain | tennant_name | https_port | smtp_port | mgmt_port | solr_port |
+----------------+--------------+------------+-----------+-----------+-----------+
| test.test.de   | test         |      10000 |     10001 |     10002 |     10003 |
+----------------+--------------+------------+-----------+-----------+-----------+

这仅适用于表中的一个租户。如果我输入第二个，我的 SELECT 视图语句返回多个结果，这会导致错误。

MariaDB [admindb]> select * from view_ausgabe;
ERROR 1242 (21000): Subquery returns more than 1 row"

这是我的 VIEW 定义

MariaDB [admindb]> CREATE VIEW view_ausgabe AS SELECT tennant_domain, tennant_name,
    -> (SELECT port from table_tennant WHERE protocol = 'https' GROUP BY tennant_name AND tennant_domain) AS https_port,
    -> (SELECT port from table_tennant WHERE protocol = 'smtp' GROUP BY tennant_name AND tennant_domain) AS smtp_port,
    -> (SELECT port from table_tennant WHERE protocol = 'mgmt' GROUP BY tennant_name AND tennant_domain) AS mgmt_port,
    -> (SELECT port from table_tennant WHERE protocol = 'solr' GROUP BY tennant_name AND tennant_domain) AS solr_port
    -> FROM table_tennant GROUP BY tennant_name;

如何在 VIEW 中为每个租户创建一个新行？

感谢您的帮助。 安德烈

【问题讨论】：

该技术称为“旋转”。

【参考方案1】：

使用条件聚合：

create view view_ausgabe as
select 
    tennant_domain,
    tennant_name,
    max(case when protocal = 'https' then port end) https_port,
    max(case when protocal = 'smtp'  then port end) smtp_port,
    max(case when protocal = 'mngt'  then port end) mngt_port,
    max(case when protocal = 'solr'  then port end) solr_port   
from mytable
group by tennant_domain, tennant_name