Query help

SQLServerCentral is supported by Red Gate Software Ltd.

Popular Topics

Home

Members

Calendar

Who's On

Home » SQL Server 2008 » T-SQL (SS2K8) » Query help

Query help

Rate Topic

Display Mode

Topic Options

Author

Message

s_osborne2

Posted Wednesday, January 23, 2013 7:39 AM

SSChasing Mays

Group: General Forum Members
Last Login: Today @ 6:15 AM
Points: 612, Visits: 1,867

Hi,

I have a query that returns a ProposalId a RiskId and RiskTaken bit flag. I've setup some test data below:

DECLARE @table TABLE
(
	ProposalId INT,
	RiskId INT,
	RiskTaken BIT
)
INSERT INTO @table
SELECT 1, 1, 1
UNION ALL SELECT 1,2,0
UNION ALL SELECT 1,3,0
UNION ALL SELECT 2,1,0
UNION ALL SELECT 2,2,0
UNION ALL SELECT 2,3,0

SELECT 
	t.[ProposalId],
	t.[RiskId],
	t.[RiskTaken]	
FROM 
	@table t

Now, what'd i'd like is another column called ProposalTaken that should be a 1 where there is a risk for that proposal that has a risktaken flag of 1. Example results shown in the attachment.

Is there a way to achieve this?

Thanks,

Simon

Follow me on Twitter: @WazzTheBadger
LinkedIn Profile: Simon Osborne

Post Attachments

Results.png (10 views, 6.31 KB)

Post #1410579

michael.higgins

Posted Wednesday, January 23, 2013 7:48 AM

Valued Member

Group: General Forum Members
Last Login: Today @ 9:42 AM
Points: 63, Visits: 474

DECLARE @table TABLE
(
	ProposalId INT,
	RiskId INT,
	RiskTaken BIT
)
INSERT INTO @table
SELECT 1, 1, 1
UNION ALL SELECT 1,2,0
UNION ALL SELECT 1,3,0
UNION ALL SELECT 2,1,0
UNION ALL SELECT 2,2,0
UNION ALL SELECT 2,3,0
;
WITH ProposalRisk
AS
(SELECT DISTINCT ProposalId FROM @table WHERE RiskTaken = 1
)

SELECT 
	t.[ProposalId],
	t.[RiskId],
	t.[RiskTaken],
	CASE
	WHEN pr.ProposalId IS NOT NULL THEN 1
	ELSE
	0
	END AS ProposalTaken 
FROM 
	@table t
	LEFT OUTER JOIN ProposalRisk pr ON t.ProposalId = pr.ProposalId

Looks like it should work

Post #1410592

s_osborne2

Posted Wednesday, January 23, 2013 9:20 AM

SSChasing Mays

Group: General Forum Members
Last Login: Today @ 6:15 AM
Points: 612, Visits: 1,867

Hi,

Thanks for you help.

I've been playing with this, and you're right it does work but doesn't give me the solution to the problem i have. I've given @table as an example here to illustrate the problem. In my real world problem @table is actually the result of a complex query and isn't stored in a table (temporary or otherwise). I have many more columns than outlined above and the query returns ~40k rows.

I was hoping to be able to do something in-line with a CROSS APPLY type solution but haven't been able to crack it. I could write the result of the query to a temporary or even a persisted table and then use the CTE as you suggest but there's write overhead invovled with that, that i'd like to avoid if possible.

Is there a way to do this without a CTE or am I hoping for a solution that simply isn't possible?

Thanks,

Simon

Follow me on Twitter: @WazzTheBadger
LinkedIn Profile: Simon Osborne

Post #1410669

Sean Lange

Posted Wednesday, January 23, 2013 9:33 AM

SSCrazy Eights

Group: General Forum Members
Last Login: Today @ 10:16 AM
Points: 8,584, Visits: 8,225

s_osborne2 (1/23/2013)

Actually the way you describe this a CTE is exactly what you want. If you use a cross apply you would have to requery your data anyway. This is exactly what CTEs were designed for.

Here is the same solution but instead of selecting directly from the table variable I setup a CTE. You would just replace the first CTE query with your complex query.

DECLARE @table TABLE
(
	ProposalId INT,
	RiskId INT,
	RiskTaken BIT
)
INSERT INTO @table
SELECT 1, 1, 1
UNION ALL SELECT 1,2,0
UNION ALL SELECT 1,3,0
UNION ALL SELECT 2,1,0
UNION ALL SELECT 2,2,0
UNION ALL SELECT 2,3,0

;with CTE_AsQueryReplacement as
(
	select * from @table --replace this with your complex query
)
,
ProposalRisk AS
(SELECT DISTINCT ProposalId FROM CTE_AsQueryReplacement WHERE RiskTaken = 1
)

SELECT 
	t.[ProposalId],
	t.[RiskId],
	t.[RiskTaken],
	CASE
	WHEN pr.ProposalId IS NOT NULL THEN 1
	ELSE
	0
	END AS ProposalTaken 
FROM 
	CTE_AsQueryReplacement t
	LEFT OUTER JOIN ProposalRisk pr ON t.ProposalId = pr.ProposalId

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

Need to split a string? Try Jeff Moden's splitter.

Cross Tabs and Pivots, Part 1 – Converting Rows to Columns
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs

Post #1410680