How to Merge 2 Rows into one by comma separate?

问题

I need to merge this individual rows to one column, I now how to merge column by comma separated,

+---------------+-------+-------+
|CID            |Flag   |Value  |
+---------------+-------+-------+
|1              |F      |10     |
|1              |N      |20     |
|2              |F      |12     |
|2              |N      |23     |
|2              |F      |14     |
|3              |N      |21     |
|3              |N      |22     |
+---------------+-------+-------+

Desired Result can be anything,

+-----------+----------------------------+    +--------------------------+
|Part Number| Value                      |    | Value                    |   
+-----------+----------------------------+    +--------------------------+
| 1         | 1|F|10 ; 1|N|20            | Or | 1|F|10 ; 1|N|20          |
| 2         | 2|F|12 ; 2|N|23 ; 2|F|14   |    | 2|F|12 ; 2|N|23 ; 2|F|14 |
| 3         | 3|N|21 ; 3|N|22            |    | 3|N|21 ; 3|N|22          |
+-----------+----------------------------+    +--------------------------+

Note:

Any hint in right direction with small example is more than enough

EDIT : I have massive data in tables like thousands of records where parent's and child relationship is present. I have to dump this into text files by comma separated values In single line as record. Think as primary record has relationship with so many other table then all this record has to be printed as a big line.

And I am trying to achieve by creating query so load can be distributed on database and only thing i have to worry about in business is just dumping logic into text files or whatever form we need in future.

回答1:

You can try to use LISTAGG and your query will look like this:

select a.cid, a.cid || listagg(a.flag || '|' || a.value, ',') 
from foo.dat a
group by a.cid

You can use different separators and of course play with how the result will be formatted.

来源：https://stackoverflow.com/questions/32617670/how-to-merge-2-rows-into-one-by-comma-separate