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Auto Increment Alphabet Expand / Collapse
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Posted Friday, May 28, 2010 10:54 PM


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Alright... here you go. First, we'll demo a way to accomplish the task and then I'll show in the post following this one why this type of numbering should NEVER be done.

The way the following code works is that it actually uses an IDENTITY column to provide a true auto-incrementing capability instead of having to do any manual sequencing. That's important because instead of using a bunch of self joins to an "external number generator" or sequencer of any kind, we can use a Computed Column, instead.

I still think this type of "numbering" is a huge mistake (see the next post down for why).

--===== Create a table with a real auto-incrementing column and
-- a persisted formula to convert it to Base 26 automatically.
-- The auto-incrementing column is "Zero Based" to keep things simple.
-- Max value = 26^7-1 = 8,031,810,175 > Largest INT
CREATE TABLE #MyHead
(
MyHeadID INT IDENTITY(0,1) NOT NULL,
Base26ID AS CHAR(MyHeadID/308915776%26+65) --26^6
+ CHAR(MyHeadID/11881376%26+65) --26^5
+ CHAR(MyHeadID/456976%26+65) --26^4
+ CHAR(MyHeadID/17576%26+65) --26^3
+ CHAR(MyHeadID/676%26+65) --26^2
+ CHAR(MyHeadID/26%26+65) --26^1
+ CHAR(MyHeadID%26+65) --26^0
PERSISTED NOT NULL,
SomeString VARCHAR(36) NOT NULL
)

--===== Add a million+1 rows of "something" to the table
-- just to prove it works.
INSERT INTO #MyHead
(SomeString)
SELECT TOP 1000001
NEWID() AS SomeString
FROM Master.sys.All_Columns ac1
CROSS JOIN Master.sys.All_Columns ac2

--===== Show what's in the table
SELECT *
FROM #MyHead




--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #930008
Posted Friday, May 28, 2010 11:28 PM


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@Ankit (or anyone else who thinks this type of "numbering" is a good idea),

Let me tell you why BASE 26 "numbering" like this is SO bad that it'll likely get your company sued... try the following code with your choice of classic "3 and 4 letter" swear words and see what you get...

SELECT * FROM #MyHead WHERE Base26ID LIKE '%CRAP%'


Every soccer mom and little old lady in the world will be out to get you and your company if these numbers ever are exposed publicly.


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #930010
Posted Saturday, May 29, 2010 12:26 AM


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Even though I still don't like this kind of "numbering", let's try things in a slightly different manner. If we remove all the vowels from the alphabet, it's a wee bit more difficult to spell swear words.

First, build the following scalar function. It's got to be scalar because we're still going to use it in a computed column. It can't be persisted, either, because it ends up being non-deterministic in this case and I haven't tried to figure out how to make it so because it actually runs faster than the previous example...

 CREATE FUNCTION dbo.Base21
--===== This function accepts an integer and returns mostly harmless
-- "numbering" using letters with all vowels removed.
-- Jeff Moden
(@Integer INT)
RETURNS VARCHAR(8) AS
BEGIN
DECLARE @Return VARCHAR(8)
;

WITH
cteAllowed AS
(
SELECT 'BCDFGHJKLMNPQRSTVWXYZ' AS Letters
)
SELECT @Return =
SUBSTRING(Letters, @Integer/1801088541%21+1, 1) --21^7
+ SUBSTRING(Letters, @Integer/85766121%21+1, 1) --21^6
+ SUBSTRING(Letters, @Integer/4084101%21+1, 1) --21^5
+ SUBSTRING(Letters, @Integer/194481%21+1, 1) --21^4
+ SUBSTRING(Letters, @Integer/9261%21+1, 1) --21^3
+ SUBSTRING(Letters, @Integer/441%21+1, 1) --21^2
+ SUBSTRING(Letters, @Integer/21%21+1, 1) --21^1
+ SUBSTRING(Letters, @Integer%21+1, 1) --21^0
FROM cteAllowed
;
RETURN @Return
END
GO

Now we can do this without all the swear words...

--===== Create a table with a real auto-incrementing column and
-- a persisted formula to convert it to Base 21 (no vowels) automatically.
-- The auto-incrementing column is "Zero Based" to keep things simple.
CREATE TABLE #MyHead
(
MyHeadID INT IDENTITY(0,1) NOT NULL,
Base21ID AS dbo.Base21(MyHeadID)
,
SomeString VARCHAR(36) NOT NULL
)

--===== Add a million+1 rows of "something" to the table
-- just to prove it works.
INSERT INTO #MyHead
(SomeString)
SELECT TOP 1000000
NEWID() AS SomeString
FROM Master.sys.All_Columns ac1
CROSS JOIN Master.sys.All_Columns ac2

--===== Show what's in the table
SELECT *
FROM #MyHead




--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #930011
Posted Tuesday, June 1, 2010 9:12 AM


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The lack of feedback on this post has me worried that the OP is actually using the alphabetic increment in the unfiltered mode. Please save your company a lawsuit and don't do it.

--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #930769
Posted Tuesday, June 1, 2010 10:26 AM
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Goodness me, i lost track of this thread and now i saw that this alpha-numbering is a huge swear-word dump-yard.. hmmm,as u said Jeff, it will invite lawsuits.. lets wait for the OP to post back his thoughts...
Post #930842
Posted Wednesday, June 2, 2010 11:28 PM
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Hi Guys,

I'm so sorry I couldn't pitch in before.


Wayne - Well, you did say you only needed it to get to AAAA. ZZZZ is much higher!


@Wayne: Desires are insatiable


Jeff - The lack of feedback on this post has me worried that the OP is actually using the alphabetic increment in the unfiltered mode. Please save your company a lawsuit and don't do it.


@Jeff: Yep .. you are right Jeff. Frankly, I didn't thought all that far. Your posts are enlightening.

As for lack on feedback on your attempts. I hope it doesn't put you both off but pardon my knowledge of Base 26 numbers. Its a new concept for me as I haven't used or, seen it being used anywhere so far & all this while I was & am actually trying to gain knowledge of Base 26 numbering system so that I can actually understand & implement your code.

Ankit
Post #931846
Posted Saturday, June 5, 2010 7:21 AM


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Thanks for the feedback, Ankit...

There's a fair bit of complexity to using a base 26 "numbering" system like this even if you don't take into account all the swear words that can be realized. I still recommend avoiding it if you can.


--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."

(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #933146
Posted Wednesday, October 2, 2013 12:42 AM
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Very Nice...thank you so much.
Post #1500664
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