MySQL Results as comma separated list - sql

Question

I need to run a query like:
SELECT p.id, p.name,
(SELECT name
FROM sites s
WHERE s.id = p.site_id) AS site_list
FROM publications p
But I'd like the sub-select to return a comma separated list, instead of a column of data. Is this even possible, and if so, how?

Answer 1

You can use GROUP_CONCAT to perform that, e.g. something like
SELECT p.id, p.name, GROUP_CONCAT(s.name) AS site_list
FROM sites s
INNER JOIN publications p ON(s.id = p.site_id)
GROUP BY p.id, p.name;

Answer 2

Now only I came across this situation and found some more interesting features around GROUP_CONCAT. I hope these details will make you feel interesting.
simple GROUP_CONCAT
SELECT GROUP_CONCAT(TaskName)
FROM Tasks;
Result:
+------------------------------------------------------------------+
| GROUP_CONCAT(TaskName) |
+------------------------------------------------------------------+
| Do garden,Feed cats,Paint roof,Take dog for walk,Relax,Feed cats |
+------------------------------------------------------------------+
GROUP_CONCAT with DISTINCT
SELECT GROUP_CONCAT(TaskName)
FROM Tasks;
Result:
+------------------------------------------------------------------+
| GROUP_CONCAT(TaskName) |
+------------------------------------------------------------------+
| Do garden,Feed cats,Paint roof,Take dog for walk,Relax,Feed cats |
+------------------------------------------------------------------+
GROUP_CONCAT with DISTINCT and ORDER BY
SELECT GROUP_CONCAT(DISTINCT TaskName ORDER BY TaskName DESC)
FROM Tasks;
Result:
+--------------------------------------------------------+
| GROUP_CONCAT(DISTINCT TaskName ORDER BY TaskName DESC) |
+--------------------------------------------------------+
| Take dog for walk,Relax,Paint roof,Feed cats,Do garden |
+--------------------------------------------------------+
GROUP_CONCAT with DISTINCT and SEPARATOR
SELECT GROUP_CONCAT(DISTINCT TaskName SEPARATOR ' + ')
FROM Tasks;
Result:
+----------------------------------------------------------------+
| GROUP_CONCAT(DISTINCT TaskName SEPARATOR ' + ') |
+----------------------------------------------------------------+
| Do garden + Feed cats + Paint roof + Relax + Take dog for walk |
+----------------------------------------------------------------+
GROUP_CONCAT and Combining Columns
SELECT GROUP_CONCAT(TaskId, ') ', TaskName SEPARATOR ' ')
FROM Tasks;
Result:
+------------------------------------------------------------------------------------+
| GROUP_CONCAT(TaskId, ') ', TaskName SEPARATOR ' ') |
+------------------------------------------------------------------------------------+
| 1) Do garden 2) Feed cats 3) Paint roof 4) Take dog for walk 5) Relax 6) Feed cats |
+------------------------------------------------------------------------------------+
GROUP_CONCAT and Grouped Results
Assume that the following are the results before using GROUP_CONCAT
+------------------------+--------------------------+
| ArtistName | AlbumName |
+------------------------+--------------------------+
| Iron Maiden | Powerslave |
| AC/DC | Powerage |
| Jim Reeves | Singing Down the Lane |
| Devin Townsend | Ziltoid the Omniscient |
| Devin Townsend | Casualties of Cool |
| Devin Townsend | Epicloud |
| Iron Maiden | Somewhere in Time |
| Iron Maiden | Piece of Mind |
| Iron Maiden | Killers |
| Iron Maiden | No Prayer for the Dying |
| The Script | No Sound Without Silence |
| Buddy Rich | Big Swing Face |
| Michael Learns to Rock | Blue Night |
| Michael Learns to Rock | Eternity |
| Michael Learns to Rock | Scandinavia |
| Tom Jones | Long Lost Suitcase |
| Tom Jones | Praise and Blame |
| Tom Jones | Along Came Jones |
| Allan Holdsworth | All Night Wrong |
| Allan Holdsworth | The Sixteen Men of Tain |
+------------------------+--------------------------+
USE Music;
SELECT ar.ArtistName,
GROUP_CONCAT(al.AlbumName)
FROM Artists ar
INNER JOIN Albums al
ON ar.ArtistId = al.ArtistId
GROUP BY ArtistName;
Result:
+------------------------+----------------------------------------------------------------------------+
| ArtistName | GROUP_CONCAT(al.AlbumName) |
+------------------------+----------------------------------------------------------------------------+
| AC/DC | Powerage |
| Allan Holdsworth | All Night Wrong,The Sixteen Men of Tain |
| Buddy Rich | Big Swing Face |
| Devin Townsend | Epicloud,Ziltoid the Omniscient,Casualties of Cool |
| Iron Maiden | Somewhere in Time,Piece of Mind,Powerslave,Killers,No Prayer for the Dying |
| Jim Reeves | Singing Down the Lane |
| Michael Learns to Rock | Eternity,Scandinavia,Blue Night |
| The Script | No Sound Without Silence |
| Tom Jones | Long Lost Suitcase,Praise and Blame,Along Came Jones |
+------------------------+----------------------------------------------------------------------------+

Answer 3

Instead of using group concat() you can use just concat()
Select concat(Col1, ',', Col2) as Foo_Bar from Table1;
edit this only works in mySQL; Oracle concat only accepts two arguments. In oracle you can use something like select col1||','||col2||','||col3 as foobar from table1;
in sql server you would use + instead of pipes.

Answer 4

In my case i have to concatenate all the account number of a person who's mobile number is unique. So i have used the following query to achieve that.
SELECT GROUP_CONCAT(AccountsNo) as Accounts FROM `tblaccounts` GROUP BY MobileNumber
Query Result is below:
Accounts
93348001,97530801,93348001,97530801
89663501
62630701
6227895144840002
60070021
60070020
60070019
60070018
60070017
60070016
60070015