Window function to expand row into multiple rows?

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Window function to expand row into multiple rows?

jallmond

Ten Centuries

Points: 1181
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February 12, 2016 at 9:32 am

#324321

I have a requirement to expand a row in an Orders table into two rows based on columns of EnteredBy and PerformedBy.
For example:
CREATE TABLE dbo.Orders
(
[OrderId] INT IDENTITY(1,1) PRIMARY KEY NOT NULL
,[OrderDate] DATETIME2(2) NOT NULL
,[CustomerName] VARCHAR(50) NOT NULL
,[SalesAmount] DECIMAL(9,2) NOT NULL
,[EnteredBy] VARCHAR(25) NOT NULL
,[PerformedBy] VARCHAR(25) NOT NULL
)
One way to expand this is to stack the results using UNION ALL.
SELECT
[OrderId] AS [OrderNumber]
,[EnteredBy] AS [User]
FROM dbo.Orders
UNION ALL
SELECT
[OrderId] AS [OrderNumber]
,[PerformedBy] AS [User]
FROM dbo.Orders
Unfortunately this reads the base table twice, so I'm wondering if there isn't a clever way to do this in a single read pass using a window function?

Viewing 5 posts - 1 through 4 (of 4 total)

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Jacob Wilkins One Orange Chip Points: 27976 More actions · Answer 1

No need to use window functions. A simple CROSS APPLY will do the trick.

SELECT [OrderNumber]=OrderID,

[User]=x.[User]

FROM dbo.Orders CROSS APPLY (SELECT [User]=EnteredBy

UNION ALL

SELECT [User]=PerformedBy

) x([User])

Cheers!

Luis Cazares SSC Guru Points: 183706 More actions · Answer 2

Jacob Wilkins (2/12/2016)
No need to use window functions. A simple CROSS APPLY will do the trick.
SELECT [OrderNumber]=OrderID,
[User]=x.[User]
FROM dbo.Orders CROSS APPLY (SELECT [User]=EnteredBy
UNION ALL
SELECT [User]=PerformedBy
) x([User])
Cheers!

Or the short version available since 2008.

SELECT [OrderNumber]=OrderID,

[User]=x.[User]

FROM dbo.Orders

CROSS APPLY (VALUES( EnteredBy),

(PerformedBy)) x([User]);

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

How to post data/code on a forum to get the best help: Option 1 / Option 2

Jacob Wilkins One Orange Chip Points: 27976 More actions · Answer 3

Luis Cazares (2/12/2016)
Jacob Wilkins (2/12/2016)
No need to use window functions. A simple CROSS APPLY will do the trick.
SELECT [OrderNumber]=OrderID,
[User]=x.[User]
FROM dbo.Orders CROSS APPLY (SELECT [User]=EnteredBy
UNION ALL
SELECT [User]=PerformedBy
) x([User])
Cheers!
Or the short version available since 2008.
SELECT [OrderNumber]=OrderID,
[User]=x.[User]
FROM dbo.Orders
CROSS APPLY (VALUES( EnteredBy),
(PerformedBy)) x([User]);

Heh, good point. Went on autopilot using the old stuff; one day I won't have to worry about 2005...one day. 🙂

Jeff Moden SSC Guru Points: 1004406 More actions · Answer 4

Jacob Wilkins (2/12/2016)
Luis Cazares (2/12/2016)
Jacob Wilkins (2/12/2016)
No need to use window functions. A simple CROSS APPLY will do the trick.
SELECT [OrderNumber]=OrderID,
[User]=x.[User]
FROM dbo.Orders CROSS APPLY (SELECT [User]=EnteredBy
UNION ALL
SELECT [User]=PerformedBy
) x([User])
Cheers!
Or the short version available since 2008.
SELECT [OrderNumber]=OrderID,
[User]=x.[User]
FROM dbo.Orders
CROSS APPLY (VALUES( EnteredBy),
(PerformedBy)) x([User]);
Heh, good point. Went on autopilot using the old stuff; one day I won't have to worry about 2005...one day. 🙂

I know it's just me but I like the "old stuff". It's just as fast as the new stuff, as well. Guess it's a matter of what you cut your teeth on.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

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