How to Comma Delimit Multiple Rows into One Column

Multiple rows to one comma-separated value in sql

Use where clause :

select name , STUFF((SELECT '; ' + facilty 
                     FROM leads  
                     FOR XML PATH('')
                    ),1,2,'') as facilty, address 
from leads
where name is not null;

How to concatenate text from multiple rows into a single text string in SQL Server

If you are on SQL Server 2017 or Azure, see Mathieu Renda answer.

I had a similar issue when I was trying to join two tables with one-to-many relationships. In SQL 2005 I found that XML PATH method can handle the concatenation of the rows very easily.

If there is a table called STUDENTS

SubjectID       StudentName
----------      -------------
1               Mary
1               John
1               Sam
2               Alaina
2               Edward

Result I expected was:

SubjectID       StudentName
----------      -------------
1               Mary, John, Sam
2               Alaina, Edward

I used the following T-SQL:

SELECT Main.SubjectID,
       LEFT(Main.Students,Len(Main.Students)-1) As "Students"
FROM
    (
        SELECT DISTINCT ST2.SubjectID, 
            (
                SELECT ST1.StudentName + ',' AS [text()]
                FROM dbo.Students ST1
                WHERE ST1.SubjectID = ST2.SubjectID
                ORDER BY ST1.SubjectID
                FOR XML PATH (''), TYPE
            ).value('text()[1]','nvarchar(max)') [Students]
        FROM dbo.Students ST2
    ) [Main]

You can do the same thing in a more compact way if you can concat the commas at the beginning and use substring to skip the first one so you don't need to do a sub-query:

SELECT DISTINCT ST2.SubjectID, 
    SUBSTRING(
        (
            SELECT ','+ST1.StudentName  AS [text()]
            FROM dbo.Students ST1
            WHERE ST1.SubjectID = ST2.SubjectID
            ORDER BY ST1.SubjectID
            FOR XML PATH (''), TYPE
        ).value('text()[1]','nvarchar(max)'), 2, 1000) [Students]
FROM dbo.Students ST2

Concatenate few rows into a single row with comma seperated using string_agg in postgreSQL

Give this a shot:

select visit_id, string_agg(page_name, ',' order by sequence_number) as cart_items                        
from events e 
join page_hierarchy ph on e.page_id = ph.page_id 
join event_identifier ei on ei.event_type = e.event_type
where event_name = 'Add to Cart'
group by visit_id

The order by sequence_number within the string_agg(...) function will sort your comma separated output based on sequence number.

Here's an example with the sample data you provided:
https://dbfiddle.uk/?rdbms=postgres_13&fiddle=52077d5be605a51d3a7bb14152a392df

Here're the results of that:

visit_id | cart_items   
:------- | :------------
d58cbd   | Kingfish,Tuna

How can I combine multiple rows into a comma-delimited list in Oracle?

Here is a simple way without stragg or creating a function.

create table countries ( country_name varchar2 (100));

insert into countries values ('Albania');

insert into countries values ('Andorra');

insert into countries values ('Antigua');


SELECT SUBSTR (SYS_CONNECT_BY_PATH (country_name , ','), 2) csv
      FROM (SELECT country_name , ROW_NUMBER () OVER (ORDER BY country_name ) rn,
                   COUNT (*) OVER () cnt
              FROM countries)
     WHERE rn = cnt
START WITH rn = 1
CONNECT BY rn = PRIOR rn + 1;

CSV                                                                             
--------------------------
Albania,Andorra,Antigua                                                         

1 row selected.

As others have mentioned, if you are on 11g R2 or greater, you can now use listagg which is much simpler.

select listagg(country_name,', ') within group(order by country_name) csv
  from countries;

CSV                                                                             
--------------------------
Albania, Andorra, Antigua

1 row selected.

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