Round

  • Pradyothana Shastry

    SSCertifiable

    Points: 5211

    Comments posted to this topic are about the item Round

  • tommyh

    SSCertifiable

    Points: 6222

    Nice question. Though the explanation isnt entirely accurate. Its not rounded, its truncated.

    If the question had been, lets say

    declare @r decimal(5,2)

    set @r= round(5/3.2,1,3)

    select @r

    Then we would get 1.5 wheras a round would have given us 1.6 (change last parameter in Round to 0... or remove it all together).

  • SQLRNNR

    SSC Guru

    Points: 281107

    thanks for the question

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

  • honza.mf

    SSCertifiable

    Points: 5519

    tommyh (9/16/2010)


    Nice question. Though the explanation isnt entirely accurate. Its not rounded, its truncated.

    If the question had been, lets say

    declare @r decimal(5,2)

    set @r= round(5/3.2,1,3)

    select @r

    Then we would get 1.5 wheras a round would have given us 1.6 (change last parameter in Round to 0... or remove it all together).

    Right, the 3rd parameter of round is the most important one. It's value 3 is not typical but greater than zero.



    See, understand, learn, try, use efficient
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  • Koen Verbeeck

    SSC Guru

    Points: 258859

    Good question, but a real easy one since all the rounding questions of Hugo Kornelis. 🙂

    It would've been more a challenge if you used 3.2 or 3.0, as someone already suggested in this thread.

    Need an answer? No, you need a question
    My blog at https://sqlkover.com.
    MCSE Business Intelligence - Microsoft Data Platform MVP

  • cengland0

    SSCertifiable

    Points: 6102

    I got it right but hesitated to click the submit button. It was too easy and I was looking for the tricky part of the question. I've been bitten by so many QOTDs with an obscure typo or something else tricky.

  • Daniel Bowlin

    SSC-Dedicated

    Points: 34566

    Good question. Round is a function with a few gotchas that it is important to know about and understand. Thanks.

  • Dave62

    SSCertifiable

    Points: 6222

    cengland0 (9/17/2010)


    ... I've been bitten by so many QOTDs with an obscure typo or something else tricky.

    I like composing questions that are on the tricky side. Must be because of all my bad experiences with certification exams.

    If it's of any consolation, the editors here do have a limit to what they will tolerate for trick questions. I submitted one a few months ago that never got published.

    I get it. The QOTDs are more about the learning experience than the certification experience.

    I'm working on one now that's a little more tame... 🙂

  • hrvoje.piasevoli

    Ten Centuries

    Points: 1377

    The hardest part of the question was figuring out what is the result of 5/3.1

    IMHO the point of the question would make more sense if it had been changed to 5/3.0 as the result of the function would actually be affected by the third parameter of the ROUND function unlike in this question.

    To illustrate:

    select

    Example = 'Your example'

    ,input_data = '5/3.1'

    ,Truncation = ROUND(1.612903, 1, 1) -- 1.600000

    ,Rounding = ROUND(1.612903, 1, 0) -- 1.600000

    union all

    select

    'Better example'

    ,'5/3.0'

    ,ROUND(1.666666,1,1) -- 1.600000

    ,ROUND(1.666666,1,0) -- 1.700000

    Example input_data Truncation Rounding

    -------------- ---------- ------------ ----------

    Your example 5/3.1 1.600000 1.600000

    Better example 5/3.0 1.600000 1.700000

    Regards,

    Hrvoje Piasevoli

    Hrvoje Piasevoli

  • john.arnott

    SSChampion

    Points: 11882

    honza.mf (9/17/2010)


    tommyh (9/16/2010)


    Nice question. Though the explanation isnt entirely accurate. Its not rounded, its truncated.

    If the question had been, lets say

    declare @r decimal(5,2)

    set @r= round(5/3.2,1,3)

    select @r

    Then we would get 1.5 wheras a round would have given us 1.6 (change last parameter in Round to 0... or remove it all together).

    Right, the 3rd parameter of round is the most important one. It's value 3 is not typical but greater than zero.

    Just to be picky, it's not because the third parameter is greater than zero, but because it is not equal to zero. Here's the entry in BOL for SQL 2005:

    Syntax

    ROUND ( numeric_expression , length [ ,function ] )

    Arguments

    numeric_expression

    Is an expression of the exact numeric or approximate numeric data type category, except for the bit data type.

    length

    Is the precision to which numeric_expression is to be rounded. length must be tinyint, smallint, or int. When length is a positive number, numeric_expression is rounded to the number of decimal positions specified by length. When length is a negative number, numeric_expression is rounded on the left side of the decimal point, as specified by length.

    function

    Is the type of operation to perform. function must be tinyint, smallint, or int. When function is omitted or has a value of 0 (default), numeric_expression is rounded. When a value other than 0 is specified, numeric_expression is truncated.

  • niki-659689

    Valued Member

    Points: 57

    Very Nicely Explained!!

    Thanks.

  • terrykzncs

    Ten Centuries

    Points: 1304

    Thanks for the question.

    I hardly use math functions at work, so its sometimes a shock that these simple functions can be so tricky..... A misunderstood (or missing) parameter would mean that the calculations would be inaccurate:w00t:

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