SQL Server array_agg (master - detail) - sql-server

Question

How can I convert this PostgreSQL code to SQL Server ?
select
countries.title,
(select array_to_json(array_agg(row_to_json(t)))
from postcodes t
where t.country_id = countries.id) as codes
from countries
My initial problem is that I need to select complete master table and with each row all details.
Countries:
id title
1 SLO
2 AUT
PostCodes:
id country_id code title
1 1 1000 Lj
2 1 2000 Mb
3 2 22180 Vi
4 2 22484 De
Desired result:
1 SLO 1000;Lj|2000;MB
2 AUT 22180;Vi|22484;De
Not:
1 SLO 1000 Lj
1 SLO 2000 Mb
2 AUT 22180 Vi
2 AUT 22484 De
The best solution would be using FOR JSON, but unfortunately I need support for 2008 or at least 2012.
With left join all master data are duplicated for detail count, but I do not want to do this. Even worse it would be to select all countries and then call select on post_codes for every country in for loop.

Answer 1

select countries.title,
STUFF((select '|' + t.code + ';' + t.title
from postcodes t
where t.country_id = countries.id
FOR XML PATH('')
),1,1,'') as codes
from countries
-- CAST t.code to VARCHAR if it's Number

Answer 2

try this:
Select Main.COUNTRY_ID,c.title,Left(Main.POSTCODES,Len(Main.POSTCODES)-1) As "POSTCODES"
From
(
Select distinct ST2.COUNTRY_ID,
(
Select ST1.CODE+';'+ST1.TITLE + '|' AS [text()]
From dbo.POSTCODES ST1
Where ST1.COUNTRY_ID = ST2.COUNTRY_ID
ORDER BY ST1.COUNTRY_ID
For XML PATH ('')
) [POSTCODES]
From dbo.POSTCODES ST2
) [Main]
inner join countries c on c.id=main.country_id

Answer 3

Using XML PATH for concatenation can increase the complexity of your code. It's better to implement a CLR aggregation function. Then, you can do the following:
SELECT C.[id]
,C.[title]
,REPLACE([dbo].[Concatenate] (P.[code] + ';' + P.[title]), ',', '|')
FROM #Countries C
INNER JOIN #PostCodes P
ON C.[id] = p.[country_id]
GROUP BY C.[id]
,C.[title];
You can create your own version of the concatenate aggregate - you can specify the delimiter, the order, etc. I can show you examples if you want.
DECLARE #Countries TABLE
(
[id] TINYINT
,[title] VARCHAR(12)
);
INSERT INTO #Countries ([id], [title])
VALUES (1, 'SLO')
,(2, 'AUT');
DECLARE #PostCodes TABLE
(
[id] TINYINT
,[country_id] TINYINT
,[code] VARCHAR(12)
,[title] VARCHAR(12)
);
INSERT INTO #PostCodes ([id], [country_id], [code], [title])
VALUES (1, 1, 1000, 'Lj')
,(2, 1, 2000, 'Mb')
,(3, 2, 22180, 'Vi')
,(4, 2, 22484, 'De');
SELECT C.[id]
,C.[title]
,REPLACE([dbo].[Concatenate] (P.[code] + ';' + P.[title]), ',', '|')
FROM #Countries C
INNER JOIN #PostCodes P
ON C.[id] = p.[country_id]
GROUP BY C.[id]
,C.[title];