concatenate a column on one line depends on a id

问题

I've again a basic question :

If I do :

SELECT DISTINCT id, date, doctext, docline, from documentation where date in (02/14/2017)

doctext is a char(80) and I cannot change it. The problem of this columns is the size, I cannot save a value > 80 characters, If the doc is > 80 char, it will save two lines in SQL and upgrade the docline

So my result is, for example :

0 2017-02-14 this is a basic test to show you the result 0
1 2017-02-14 this is a new basic test to show you the result 0
2 2017-02-14 this is a  long basic test to show you the result 0
2 2017-02-14 when the documentation have multiple lines 1

What I'm trying to do is to concatenate doctext if the result have multiple line with the same id So the result should be :

0 2017-02-14 this is a basic test to show you the result 
1 2017-02-14 this is a new basic test to show you the result 
2 2017-02-14 this is a  long basic test to show you the result when the documentation have multiple lines 1

Is it possible to concatenate a column on one line depends on a id ? I'm trying with CASE like :

CASE WHEN docline > 0 THEN DOCTEXT ... 

I don't know how can I spectify that I would like the next DOCTEXT

Thanks,

回答1:

Something like this should work

SELECT id, date,MAX(docline),
Ids=Stuff((SELECT ' ' + doctext  FROM documentation  d WHERE d.id=documentation.id
 FOR XML PATH (''))
             , 1, 1, '' )
 from documentation where date in (02/14/2017)
GROUP BY id,date

回答2:

For storing multiple lines you used the docline column but I didn't use it. if you want you can add it.

I used two tables(MasterTable and DetailsTable)

Master Table:

ID | Date | DocText
-----------------------------
1 2017-01-14 Hello
-----------------------------
2 2017-03-18 Good Bye
------------------------------
3 2017-02-14 Hello Iran
------------------------------
4 2017-02-14 Good Bye Iran
------------------------------

DetailsTable:

ID | DocText
---------------------------
3 How are you ?
---------------------------
4 See you ?
---------------------------

Use Test;
go

select mt.ID,mt.DocText + ' ' + ISNULL(dt.DocText,'') as DocText
from MasterTable mt
full outer join DetailsTable dt
on mt.ID=dt.ID;

It works for multiple lines.

the result:

ID | Date | DocText
--------------------------------------------
1 2017-01-14 Hello
--------------------------------------------
2 2017-03-18 Good Bye
--------------------------------------------
3 2017-02-14 Hello Iran How are you ?
--------------------------------------------
4 2017-02-14 Good Bye Iran See you ?
--------------------------------------------

来源：https://stackoverflow.com/questions/42237624/concatenate-a-column-on-one-line-depends-on-a-id