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Scaled-down SQL


Scaled-down SQL

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pksutha
pksutha
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My answer is like this
first part which is i 've answered:

Declare @value1 decimal(20,10),@value2 decimal(20,3)

SET @value1 = 1234567890.123456789
SET @value2 = 0.1

SELECT @value1 * @value2

Second part is screened answer:

DECLARE @value1 DECIMAL(20,10), @value2 DECIMAL(30,13)
SET @value1 = 1234567890.123456789
SET @value2 = 0.1

SELECT @value1 * @value2


Ans:
The screened answer is u 've declared value2 decimal(30,13)... why u need like that?
my answer is Declare @value1 decimal(20,10),@value2 decimal(20,3)...... this is enough in SQL server 2005
Duncan Pryde
Duncan Pryde
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pksutha (3/22/2011)
My answer is like this
first part which is i 've answered:

Declare @value1 decimal(20,10),@value2 decimal(20,3)

SET @value1 = 1234567890.123456789
SET @value2 = 0.1

SELECT @value1 * @value2

Second part is screened answer:

DECLARE @value1 DECIMAL(20,10), @value2 DECIMAL(30,13)
SET @value1 = 1234567890.123456789
SET @value2 = 0.1

SELECT @value1 * @value2


Ans:
The screened answer is u 've declared value2 decimal(30,13)... why u need like that?
my answer is Declare @value1 decimal(20,10),@value2 decimal(20,3)...... this is enough in SQL server 2005


That's kind of the "moral" of the question. Never use a "bigger" decimal/numeric than you actually need.
michael.kaufmann
michael.kaufmann
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Duncan Pryde (3/21/2011)
michael.kaufmann (3/21/2011)
tilew-948340 (3/20/2011)
[...]


[...]


Excellent explanation. Couldn't have put it better myself.


Thank you very much for your kind words of appreciation, Duncan.
Thanks again for your question and great explanation.

Regards,
Michael
Toreador
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Duncan Pryde (3/22/2011)
That's kind of the "moral" of the question. Never use a "bigger" decimal/numeric than you actually need.


The moral I've drawn is that maybe Floats aren't as bad as we thought...
rlswisher
rlswisher
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Declare @value1 numeric(38,10)
Declare @value2 numeric(1,1)
SET @value1 = 1234567890.123456789
SET @value2 = 0.1
SELECT @value1
SELECT @value2

SELECT @value1 * @value2
= "123456789.012345679"
Duncan Pryde
Duncan Pryde
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rlswisher (3/22/2011)
Declare @value1 numeric(38,10)
Declare @value2 numeric(1,1)
SET @value1 = 1234567890.123456789
SET @value2 = 0.1
SELECT @value1
SELECT @value2

SELECT @value1 * @value2
= "123456789.012345679"


As expected.

Result precision is 38+1+1 = 40, scale is 10+1 = 11. Max allowed precision is 38, so precision and scale are reduced by 2, giving a final result precision and scale of 38,9 - which is why the result is rounded as you can see.
Duncan Pryde
Duncan Pryde
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Toreador (3/22/2011)
Duncan Pryde (3/22/2011)
That's kind of the "moral" of the question. Never use a "bigger" decimal/numeric than you actually need.


The moral I've drawn is that maybe Floats aren't as bad as we thought...


Until you want to do something like this

Hehe
Gopi S
Gopi S
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Excellent question and nice explanation..
Learned something new that Precision and Scale varies for the resulting value
based on (+, -, / , *, [UNION | EXCEPT | INTERSECT] , % ) .

Thanks for posting this...
SQLRNNR
SQLRNNR
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great qeustion

Jason...AKA CirqueDeSQLeil
_______________________________________________
I have given a name to my pain...MCM SQL Server, MVP
SQL RNNR
Posting Performance Based Questions - Gail Shaw
Learn Extended Events

SanDroid
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Great question. You would not believe how long and how often programers get this wrong.
There is even a list that is maintained of ROM chips that do weight conversions incorrectly becuase Dec(6,2) is used instead of Dec(13,5)

I even had to "show the math" on this exact thing a year ago when I had to explain why the weight conversion code used to change Pound to Kilos and vice versa was wrong in every appliation where I work.

Not understanding this math is why so many ships have a problem balancing thier loads.
Sometimes the cargo is weighed in pounds and the balast program uses Kilos.
Then someone uses a cheap hand calculator to convert the 100,000 tons in pounds to Kilos and the weghts off by at least 1,000 tons.
Go


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