Concat all column values in sql

Question

How to concat all column values from differenct rows returned from a sql query into one value? This is an example:

a query returns:

FOO
------
RES1

RES2
         


        

Answer 1

SQL Server 2008 R2:

declare @ColumnNameList VARCHAR(MAX)


 SELECT @ColumnNameList  = COALESCE(@ColumnNameList +',' ,'') + ColumnName 
                     FROM 
                       <<table name>>

select @ColumnNameList 

Answer 2

Select ([col1] +','+[col2]+','+ [col3]+','+[col4]) as [MyCol] From [Table]

Answer 3

In SQL Server:

SELECT  col1 AS [text()]
FROM    foo
FOR XML PATH ('')

In MySQL:

SELECT  GROUP_CONCAT(col1 SEPARATOR '')
FROM    foo

In PostgreSQL:

SELECT  array_to_string
        (
        ARRAY
        (
        SELECT  col1
        FROM    foo
        ), ''
        )

In Oracle:

SELECT  *
FROM    (
        SELECT  col1, ROW_NUMBER() OVER(ORDER BY 1) AS rn
        FROM    foo
        MODEL
        DIMENSION BY
                (rn)
        MEASURES
                (col1, col1 AS group_concat, 0 AS mark)
        RULES UPDATE (
                group_concat[rn > 1] =  group_concat[CV() - 1] || col1[CV()],
                mark[ANY] = PRESENTV(mark[CV() + 1], 0, 1)
                )
        )
WHERE   mark = 1

Answer 4

Quassnoi's Oracle solution is quite impressive, but I found simpler ones using SYS_CONNECT_BY_PATH() rather than the MODEL magic.

SELECT REPLACE(MAX(SYS_CONNECT_BY_PATH(foo, '/')), '/', '') conc
FROM (
    SELECT T_FOO.*, ROW_NUMBER() OVER (ORDER BY FOO) R FROM T_FOO
)
START WITH r=1
CONNECT BY PRIOR r = r-1;

Answer 5

I found the answer on How to concatenate all the records in a column returned by a query into one varchar string in T-SQL?

declare @s varchar(8000)
select @s = coalesce(@s + col, col) from tbl

This should solve

Answer 6

Assuming that it's one column with multiple values, this approach works for MS SQL Server (I can't speak for other systems).

declare @result varchar(max)
set @result = ''

select @result = @result + RES
from (query goes here)