How to transform this result?

Question

Post reply

How to transform this result?

yingchai

SSCommitted

Points: 1669
More actions
September 20, 2012 at 2:15 am

#261821

Hi SQL Gurus,
I have this default master data table below:
ITEM | CNT | DESCRIPTION
----------------------------------------
HMMEDA | | HYH Med Oil
HMMEDA | G01 | HYH Med Oil No 1 (56ml)
HMMEDA | G02 | HYH Med Oil No 2 (96ml)
HMMEDA | G03 | HYH Med Oil No 3 (136ml)
How can I transform into this view below by adding an item description column to represent the item code?
ITEM | ITEM_DESC | CNT | DESCRIPTION
----------------------------------------
HMMEDA | HYH Med Oil | | HYH Med Oil
HMMEDA | HYH Med Oil | G01 | HYH Med Oil No 1 (56ml)
HMMEDA | HYH Med Oil | G02 | HYH Med Oil No 2 (96ml)
HMMEDA | HYH Med Oil | G03 | HYH Med Oil No 3 (136ml)
p/s: In my real database, I will have many types of item code in the ITEM column.
Below is the DDL and sample data:
DECLARE @ITEM TABLE
(
ITEM CHAR(10) NOT NULL,
CNT CHAR(3) NOT NULL,
DESCRIPTION CHAR(50) NOT NULL
)
INSERT @ITEM
VALUES ('HMMEDA', '', 'HYH Med Oil'),
('HMMEDA', 'G01', 'HYH Med Oil No 1 (56ml)'),
('HMMEDA', 'G02', 'HYH Med Oil No 2 (96ml)'),
('HMMEDA', 'G03', 'HYH Med Oil No 3 (136ml)')
Thanks 🙂

Viewing 3 posts - 1 through 2 (of 2 total)

You must be logged in to reply to this topic. Login to reply

Mark Cowne One Orange Chip Points: 26952 More actions · Answer 1

SELECT a.ITEM,b.DESCRIPTION AS ITEM_DESC,a.CNT,a.DESCRIPTION

FROM @ITEM a

INNER JOIN @ITEM b ON b.CNT='' AND b.ITEM=a.ITEM

____________________________________________________

Deja View - The strange feeling that somewhere, sometime you've optimised this query before

How to get the best help on a forum

http://www.sqlservercentral.com/articles/Best+Practices/61537

Dwain Camps SSC Guru Points: 86948 More actions · Answer 2

Here's another method that uses a correlated subquery:

SELECT ITEM

,ITEM_DESC=(

SELECT DESCRIPTION

FROM @ITEM b

WHERE a.ITEM = b.ITEM AND CNT='')

,CNT

,DESCRIPTION

FROM @ITEM a

The INNER JOIN method is probably faster but it also may depend on indexing and primary key field(s).

My mantra: No loops! No CURSORs! No RBAR! Hoo-uh![/I]
My thought question: Have you ever been told that your query runs too fast?

My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.

Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
[url url=http://www.sqlservercentral.com/articles/St