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GarDebs2010
Starting Member
4 Posts |
 Posted - 09/30/2010 : 10:32:13
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Hi,
I've been racking my brain on this one for a little while and thought I reach out and ask for some help...
Using the script below... how can I get my data to look like the expected output shown here... I've been playing with recursive CTE's but not making much progress. Any help would be greatly appreciated.
Cheers
Gary
Expected Output
Region........................Oil-producing countries
----------------------- --------------------------------------
Central America............Mexico,Guatemala,Nicaragua,Belize
Eastern Africa..............Zambia,Madagascar
Script
CREATE DATABASE [TestDb]
GO
USE [TestDb]
GO
/****** Object: Table [dbo].[OilProducers] Script Date: 09/30/2010 15:23:49 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[OilProducers](
[OilProducer_ID] [int] IDENTITY(1,1) NOT NULL,
[Country] [varchar](30) NOT NULL,
[BarrelsPerDay] [int] NOT NULL,
[Continent] [varchar](80) NOT NULL,
[Region] [varchar](80) NOT NULL
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[OilProducers] ON
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (28, N'Mexico', 3824000, N'Latin America and the Caribbean', N'Central America')
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (75, N'Guatemala', 16370, N'Latin America and the Caribbean', N'Central America')
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (79, N'Nicaragua', 14300, N'Latin America and the Caribbean', N'Central America')
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (95, N'Belize', 2413, N'Latin America and the Caribbean', N'Central America')
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (106, N'Zambia', 140, N'Africa', N'Eastern Africa')
INSERT [dbo].[OilProducers] ([OilProducer_ID], [Country], [BarrelsPerDay], [Continent], [Region]) VALUES (109, N'Madagascar', 91, N'Africa', N'Eastern Africa')
SET IDENTITY_INSERT [dbo].[OilProducers] OFF
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Transact Charlie
Flowing Fount of Yak Knowledge
United Kingdom
3448 Posts |
Posted - 09/30/2010 : 10:36:06
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Why is this table un-normalised?
(why is there not a table of Regions? with a link from this table to a regions table.
Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION |
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GarDebs2010
Starting Member
4 Posts |
Posted - 09/30/2010 : 10:41:52
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This is just a sample table and not a working example hence why is isn't normalised.. just looking for help for help in relation to this specific problem.
Cheers
quote:
Originally posted by Transact Charlie
Why is this table un-normalised?
(why is there not a table of Regions? with a link from this table to a regions table.
Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION
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Transact Charlie
Flowing Fount of Yak Knowledge
United Kingdom
3448 Posts |
Posted - 09/30/2010 : 10:42:19
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Here's one way
SELECT
region.[RegionName] AS [Region]
, LEFT(countries.[Countries], LEN(countries.[Countries]) -1) AS [Oil-producing countries]
FROM
(
SELECT DISTINCT [Region] AS [RegionName] FROM OilProducers
)
AS region
CROSS APPLY (
SELECT op.[Country] + ','
FROM OilProducers AS op
WHERE op.[Region] = region.[RegionName]
ORDER BY op.[Country]
FOR XML PATH ('')
)
AS countries ([Countries])
It would be easier (and more efficient) with a normalised approach and a region table with a foreign key from oilProducers. (you wouldn't need the SELECT DISTINCT... derived table)
Results:
Region Oil-producing countries
Central America Belize,Guatemala,Mexico,Nicaragua
Eastern Africa Madagascar,Zambia
Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION |
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GarDebs2010
Starting Member
4 Posts |
Posted - 09/30/2010 : 10:45:07
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Fairplay, ten-out-of-ten! You certainly live up to your name... that works a treat!
quote:
Originally posted by Transact Charlie
Here's one way
SELECT
region.[RegionName] AS [Region]
, LEFT(countries.[Countries], LEN(countries.[Countries]) -1) AS [Oil-producing countries]
FROM
(
SELECT DISTINCT [Region] AS [RegionName] FROM OilProducers
)
AS region
CROSS APPLY (
SELECT op.[Country] + ','
FROM OilProducers AS op
WHERE op.[Region] = region.[RegionName]
ORDER BY op.[Country]
FOR XML PATH ('')
)
AS countries ([Countries])
It would be easier (and more efficient) with a normalised approach and a region table with a foreign key from oilProducers. (you wouldn't need the SELECT DISTINCT... derived table)
Results:
Region Oil-producing countries
Central America Belize,Guatemala,Mexico,Nicaragua
Eastern Africa Madagascar,Zambia
Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION
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Transact Charlie
Flowing Fount of Yak Knowledge
United Kingdom
3448 Posts |
Posted - 09/30/2010 : 10:48:50
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the FOR XML PATH('') method for row concatenation is a bit of a hack.
Presentation like this should be handled in your front end. It's easier (and more performant) to simply return an ordered list from the database and then iterate of the rows building up output in whatever application language you are using..
My comments about the normalisation still all apply but I get the impression you know what you are doing.
good luck
Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION |
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Topic |
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Recursive CTE's - Please help!
