'stuff' 和 'for xml path('')' 来自 Postgresql 服务器中的 SQL 服务器

Question

I'm migrating some SQL Server 2008R2 queries to Postgresql 9.0 and I have some trouble with it. Here's the SQL Server query:

stuff((select ', '+p.[NAME] as 'data()' 
from BPROVIDERS_PROVIDER p, BORDER_ARTICLEORDERPROVIDER aop 
where p.OID = aop.PROVIDER for xml path('')),1,1,'')) as pNAMES

Reading SQL Server documentation I understand that this creates a comma separated list. I think that I can change stuff function to overlay function in Postresql'. Am I correct?

The second problem comes with SQL Server's for xml path with ('') as a parameter. It returns the values assigned to an attribute called pNAMES instead of create row elements. Is that correct?

Does Postgresql Query_to_xml() function with attribute tableforest = 'true' do the same?

Thank you.

Answer 1

You can use string_agg instead.

SQL Fiddle

PostgreSQL 9.1.6 Schema Setup :

create table T
(
  Name varchar(10)
);

insert into T values('Kalle');
insert into T values('Pelle');
insert into T values('Urban');

Query 1 :

select string_agg(Name, ',') as Names
from T

Results :

|             NAMES |
---------------------
| Kalle,Pelle,Urban |

Answer 2

You can replace it by String_agg for example SQL Server stored procedure:

STUFF((SELECT DISTINCT ', ' + CONVERT(VARCHAR,L.ROLE_SUB_CAT_ID) 
       FROM [PHS].[dbo].PHS_ADMIN_USER_ACCESS_DTL K,
            [PHS].[dbo].[PHS_ADMIN_USER_ROLE_SUB_CAT_MST] L
       WHERE L.ROLE_SUB_CAT_ID = K.ROLE_SUB_CAT_ID 
         AND K.UMC_ID = A.UMC_ID 
         AND K.CCR_ID = A.CCR_ID
       FOR XML PATH('')), 1, 1, '') AS ROLE_SUB_CAT_ID

Convert it to postgresql like this:

string_agg((SELECT distinct ', ' ||  cast(L.ROLE_SUB_CAT_ID as VARCHAR) FROM PHS.dbo.PHS_ADMIN_USER_ACCESS_DTL K,
          PHS.dbo.PHS_ADMIN_USER_ROLE_SUB_CAT_MST L
          WHERE L.ROLE_SUB_CAT_ID = K.ROLE_SUB_CAT_ID AND K.UMC_ID = A.UMC_ID AND K.CCR_ID=A.CCR_ID
          ), 1, 1, '') AS ROLE_SUB_CAT_ID

Answer 3

STUFF() with XML PATH

same teble to record STUFF

SELECT distinct C.country, X.ProductList FROM     
tbl_demo as C     
CROSS APPLY    
(    
SELECT STUFF    
      (    
          (    
              SELECT 
                    distinct 
                        ',' + P.product 
                    FROM 
                        tbl_demo AS P    
                    JOIN 
                        tbl_demo AS CP 
                    ON 
                        P.country = CP.country     
                    WHERE 
                        CP.sub_id = C.sub_id    
                    FOR XML PATH('')    
          )    
              
      ,1,1,'') as ProductList    
) as X