SQL, How to Concatenate results?

Question

I currently have a SQL query that returns a number of fields. I need one f the fields to be effectively a sub query sub that.

The Problem in detail:

If I have a table X with two columns, ModuleID and say ModuleValue, how can I write a SQL query to take the results and Concatenate it into one field:

EG Results returned from

 (SELECT ModuleValue FROM Table_X WHERE ModuleID=@ModuleID)

Value 1

Value 2

Value 3

...

I need to return the result thus (as a single row, unlike the above):

Value 1, Value 2, Value 3

Is there a simple Concatenation method that could be user?

EDIT:

DB is MS TSQL (2005)

Solution 1

With MSSQL you can do something like this:

declare @result varchar(500)
set @result = ''
select @result = @result + ModuleValue + ', ' 
from TableX where ModuleId = @ModuleId

Solution 2

This one automatically excludes the trailing comma, unlike most of the other answers.

DECLARE @csv VARCHAR(1000)

SELECT @csv = COALESCE(@csv + ',', '') + ModuleValue
FROM Table_X
WHERE ModuleID = @ModuleID

(If the ModuleValue column isn't already a string type then you might need to cast it to a VARCHAR.)

Solution 3

In mysql you'd use the following function:

SELECT GROUP_CONCAT(ModuleValue, ",") FROM Table_X WHERE ModuleID=@ModuleID

I am not sure which dialect you are using.

Solution 4

In SQL Server 2005 and up, you could do something like this:

SELECT 
    (SELECT ModuleValue + ','
     FROM dbo.Modules
     FOR XML PATH('')
    ) 
FROM dbo.Modules
WHERE ModuleID = 1

This should give you something like what you're looking for.

Marc

Solution 5

In my opinion, if you are using SQL Server 2017 or later, using STRING_AGG( ... ) is the best solution:

More at:

https://stackoverflow.com/a/42778050/1260488

View more solutions

Comments

[Evernoob]

Are you wanting to just retrieve the data or update another field with it?

[Darknight]

Just Retrieving, Also its MS TSQL

[Darknight]

Thanks! I'll give this a go now, will mark you as answered if it works.

[Darknight]

seems interesting, haven't used XML path much. I'll certain play with this one. Thanks!

[Darknight]

This is what I was looking for worked just fine, many thanks!

[Darknight]

Well noted, in this case it was a varchar, but in other cases this coule well be other value types.

[suiwenfeng]

SELECT LEFT(@result,LEN(@result)-1) AS Txt

[starryknight64]

Related since it was useful for me: stackoverflow.com/questions/2567000/…

[yekanchi]

how to remove the last delimma, i mean there is still a useless , at the end

[Jose Jet]

This is actually peferct

[Wayne Conrad]

This is clever and quite elegant.