SQL Server 'ROUND' vs C# 'Math.Round'

Question

I have following SQL Server statement, I want to convert this into c#. I know there is something called Math.Round in C#. I have tried but C# returns the same results c# returns an int back. For details please check the Test & results below:

SQL SERVER

Select ROUND(SUM(someValue) / 60,0)

C#

var alpha = Math.Round(someValue / 60, 0);

Tests & Result

select ROUND(150.75, 0)
-- Result = 151.00

var alpha = Math.Round(150.75, 0);
// Result = 151

Can anyone please suggest me why its not putting .00 in the end. In real values will there be any difference. I am looking ro replace SQL with C#.

Thanks

@Remus Rusanu please read my question properly. I am asking if it will differ with real time values. — user1211185, Apr 11 '14 at 10:46
Keep in mind that what you're seeing is not a number, but rather a string representation of a number. SSMS or whatever you're using must automatically display decimal numbers with two decimal places while VS does not. It doesn't change the value, just the representation. — jmcilhinney, Apr 11 '14 at 10:47
Well, show an example with a real time value then :) As is everybody wil focus on the non-significant '.00' part — Remus Rusanu, Apr 11 '14 at 10:53
@RemusRusanu Thanks for your time focusing on 00. I got my answer :) I will update it with some real value soon. — user1211185, Apr 11 '14 at 11:09

score 4 · Accepted Answer · edited May 23 '17 at 12:00

4

As per the table on MSDN here Sql Server's ROUND() will return a decimal output for a decimal input.

The overloads of Math.Round return either decimal or double, depending on the input type.

The reason why you aren't seeing .00 therefore must be as a result of the formatting you are applying to the result.

(Speculative, but the default formatting on string.Format or Debug.Writeline may internally be using a technique such as this to retrieve the number of decimal places and provide a default presentation), e.g.

int count = BitConverter.GetBytes(decimal.GetBits(Math.Round(150.75M, 0))[3])[2];

edited May 23 '17 at 12:00

Community

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answered Apr 11 '14 at 10:43

StuartLC

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thanks, will it make in difference with real time values. Because I am planning to replace a logic written in SQL with C#? – user1211185 Apr 11 '14 at 10:45
Depends what kind of precision you need - are you working with exact values or can you allow some error at high numbers of DP? – Charleh Apr 11 '14 at 10:47
See this post for more info, might clarify which datatype you need (I'm thinking decimal) http://stackoverflow.com/questions/1165761/decimal-vs-double-which-one-should-i-use-and-when – Charleh Apr 11 '14 at 10:49

score 1 · Answer 2 · answered Apr 11 '14 at 10:43

SQL is giving you the same datatype you put in - there is a precision setting for a decimal datatype in SQL and since you are specifying an number with 2dp, SQL returns a value with 2dp.

.NET doesn't share the same data types as SQL and is therefore returning a double (since you didn't specify the input as decimal)

SQL Server 'ROUND' vs C# 'Math.Round'

2 Answers2