Should Floating Point Calculations Be Doing In Sql Or C#?
Jul 20, 2005
Hi,
I would like to know, if I need to do some floting point operations
(mainly multiplication and division) on each roll of a table, should I
read the data out from the DB and do the calculation with a programming
language, say C#, or should I just use sql to do it on the sql server.
An obvious advantage of doing it in the sql server is that you dont
need to transfer the data between the sql server and he application
server.
But I am not sure if there are any other factors that will override
this advantage: like the performance of doing lots of floting point
operations in sql server.
How is the performance of doing floting point operations in sql server
comparing to C# or other languages?
Also are there any other factors that should be considered for this
case and
are there any other advantages to do this is sql server or in c#?
Thanks
Benny
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Nov 9, 2001
Hello all,
I can't see any reason for this error, not having a high level understanding of maths I thought I'd post it and hope someone could share some light on it.
I yesterday got called by a client who said that a payment for £15 + VAT was being passed to their payment gateway as 17.62 when it should be 17.63. The VAT calculation is performed in a SQL Server 2000 stored procedure. In the end I tracked it down and it wasn't a propblem with my calculation.
The price was coming out as 17.63 fine. The stored procedure then had to return this price in pence (17.63 * 100 = 17.63). When I put in a print statement with this calculation it was correct but when I output the variable that the result was assigned to it was coming out as 1762.
The variable that the result was being put into was of real datatype.
I then wrote a udf to test this. Here is the function:
CREATE FUNCTION dbo.POUNDS_TO_PENCE
(
@POUNDVALUE real
)
RETURNS INTEGER
AS
BEGIN
RETURN @POUNDVALUE * 100
END
As you can see nothing very special.
If you run this runction and pass in 17.63 it will return 1762!!!
The bit I don't get is if I change the @POUNDSVALUE intput variable to type float it returns the correct amount.
I've also found that the same problem occurs when passing in £30 + VAT (35.25) + 1pence. So, 35.26 comes out as 3525 instead of 3526. This is the case if you keep doubling the number (and adding a few pence here and there).
Does anyone know why this is or is it a bug in the processor?
The SQL books online say the following about the float and real data types:
--------------------------------------------------------
float and real (T-SQL)
Approximate number data types for use with floating point numeric data. Floating point data is approximate; not all values in the data type range can be precisely represented.
Syntax
float[(n)]
Is a floating point number data from - 1.79E + 308 through 1.79E + 308. n is the number of bits used to store the mantissa of the float number in scientific notation and thus dictates the precision and storage size. n must be a value from 1 through 53.
n is Precision Storage size
1-24 7 digits 4 bytes
25-53 15 digits 8 bytes
The Microsoft® SQL Server™ float[(n)] data type conforms to the SQL-92 standard for all values of n from 1 to 53. The synonym for double precision is float(53).
real
Floating point number data from –3.40E + 38 through 3.40E + 38. Storage size is 4 bytes. In SQL Server, the synonym for real is float(24).
--------------------------------------------------------
Apart from the fact that it says 'Approximate number data types' I can't see any difference between the data type apart from the ranges.
Anyone any ideas?
Thanks
Tom Holder
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Dec 4, 2013
I am trying to understand why SQL Server gives me significantly lower precision than many of the other sources that have tried when using the POWER function. My environment is 2008 R2 SP2 (10.50.4000.0 X64, Standard edition) on Windows 2008 X64 SP1
DECLARE @x FLOAT(53) = 1.0004;
DECLARE @y FLOAT(53) = 1.0/12.0;
SELECT POWER(@x,@y)-1; -- Answer: 3.33270904724348E-05
GO
DECLARE @x FLOAT(24) = 1.0004;
DECLARE @y FLOAT(24) = 1.0/12.0;
[URL] ....
Answer: 3.33272237835747E-05
I also tried using Windows Calculator.Answer:3.3327223783495255846580902358195e-5
And an online "high-precision" calculator from [URL] ...
Answer: 3.332722378349525584658E-5
The best SQL results compare only to the fourth digit with other results. Everything else agrees to the 10th or 12th digit.
Is the precision of arithmetic calculations on SQL Server that bad, or am I doing something wrong here? Is there another more precise alternative?
I did the following. The results speak for themselves
DECLARE @x FLOAT(53) = 1.0004;
DECLARE @y FLOAT(53) = 1.0/12.0;
DECLARE @z FLOAT(53) = POWER(@x,@y)-1; -- Answer: 3.33270904724348E-05
SELECT POWER((1+@z),12); -- 1.00039999839968
-- using results from other sources (c#, windows calc, casio.com)
SELECT POWER((1+3.33272237835747E-05),12) -- 1.0004
SELECT POWER((1+3.3327223783495255846580902358195e-5),12)-- 1.0004
SELECT POWER((1+3.332722378349525584658E-5),12) -- 1.0004
It is not important what I am trying to do, but in case it will work, I am trying to calculate the monthly return for a 90-day T-bill given the compounded annual return. x is the annualized return.
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Jan 21, 2008
I need to write a floating point value to a column in a SQL server database. I have the following line ofcode, that formats the float value before passing it off to the stored procedure.
Please look at the line of code below. Does the 8 after SqlDbType.Foat mean that this will be a floatingpoint with 8 signigicant digits past the decimal point?
mySqlCommand.Parameters.Add("@Price", SqlDbType.Float, 8).Value = float.Parse(InitialPrice);
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Mar 24, 2004
How can I truncate a floating point number to required number of decimal points
Eg:
100.642364074 to 100.64 and 67.643929847 to 67.645
Thanks.
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Oct 8, 2007
Hi.
Intermittently, the following error has been displayed when a SQL job on our box (SQL Server 2000 Service Pack 4 running on Windows 2000) runs.
'A floating point exception occurred in the user process. Current transaction is canceled.' The error number given is 3628 though I've also seen a 4xxx number (not at machine at the moment so cant be precise for the latter).
The intermittent problem over the last two days has become more regular and now does not appear to be related solely to the SQL job. For example, when connecting to the box using my local copy of SQL 2005 Management Studio and I attempt to browse the database objects I get this problem.
To the best of my knowledge, this server has not had any software installed on it and/or nothing has changed on it recently.
It has now got to the point that this particular job no longer runs. The job in question, in case this is significant, is a vanilla stored proc that returns data using OPEN ROWSET to communicate with an Access database (this connectivity has been verified to be okay, in that other similar jobs all run just fine)
If anybody can shed some light and/or point me in the right direction I would be extremely grateful.
Cheers
CG
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Jul 20, 2005
I'm trying to perform a calculation on a field in SQL Server thatshould return a value with a decimal point. My problem is that thevalue returned is truncated without the decimal point. Is there asetting that needs to be turned on in SQL server to allow this?for exampleSelect 20/3should return 6.6666667but instead I get 6
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Apr 28, 2008
Hi all
I'm a newbie in SQL server and please excuseme for this silly question, Could anyone tell me when i should use which of the following types:
Decimal
Float
Real
I've mixed up !!! all of them can have floating point BUT what's the difference? some advise please!
Thanks in advance.
Kind Regards.
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Jan 20, 2008
Hi SQL people,
I have rating system on pages in my website, each page being rated one to five by users. At the back end, an ASP.NET page displays the average rating and number of ratings for each page. As the rating is stored as an integer, the SQL statement returns an integer average. I would like to get a floating point average. Currently the statement used to return the average looks like this:
select AVG(Rating) as AverageRating from Ratings where [RatingPage] = @RatingPage
Is there a simple way to modify this to return a floating point average without iterating through the records, or converting the Rating field to a float?
Thanks for helping!
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Feb 12, 2004
I have the following query:
SELECT AVG(respondent_question.answer)
Now, the 'answer' column is an integer. However, I want the query to return a floating point number with one decimal place (i.e., 5.4, 2.3)
Since the column is an integer, the query returns only an integer by rounding to the nearest integer. How can I do this? Thanks!
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Oct 26, 2006
Hi,
I got below error in the SQL Server Production Server and i checked in the microsoft site it needs to install SQL Server service pack 4 to resolve the
problem.
"A floating point exception occurred in the user process. Current transaction is canceled"
I need help that i want to reproduce this below problem in the SQL Server environment and tried several ways but no luck.
Please advise me how to reproduce the problem.
Would be appreciate your help.
Regards
Sathish
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Oct 27, 2006
I'm having a problem that I think is due to corrupt data. Depending on
the column I use in my order by clause two problems are occuring.
1. No results are returned and I get this error:
A floating point exception occured in the user process.
2. Results are returned but there are a different number of rows depending on which columns I use in my Order By clause.
Examples
SELECT * FROM SymbolStats
ORDER BY calc_date, symbol
Returns - 12207 rows but only includes one of the 25 dates in the table.
----------
SELECT * from SymbolStats
ORDER BY current_hv
Returns - 0 rows.
----------
SELECT * from SymbolStats
ORDER BY average_hv
Returns - floating point error
With more conditions in the WHERE clause the number of results returned varies greatly.
The
fact that different numbers of rows can be returned from the same query
only differing in how they are ordered seems like a bug.
Does this sound like corrupt data? If so, what are the best methods for fixing it?
Thanks,
patrick
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Sep 21, 2005
I'm getting this error:
System.Data.SqlClient.SqlException: A floating point exception occurred in the
user process. Current transaction is canceled. at
System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping
tableMapping) at ...etc etc
when updating one particular table, but not when updating another using nearly the same code.
I've searched and searched on the inet, but with no joy.
Microsoft have several different manifestations of it, under various
different circumstances, but the solutions all seem to involve
installing SP4, which by the looks of it is a massive procedure that
you have to go to university to be competent to do.
In any case, according to Enterprise Manager, I already have SP4
included. On the other hand, the one file of mine I checked the date of
against MS's hotfix file list was 2002 not 2003, so who knows?
My Service Manager is v 8.00.760, and it's the Development Edition (ie it's all running on the one machine).
According to the info on sqlDataAdaptor.update, the
sqlError that gets returned as part of the sqlException contains
fields Class, which gives the seriousness of the error, and State,
which identifies the exact error. I get Class=16 (user-fixable)
and State=1, which we have to go to SQL Books Online to discover the
meaning of. SQL BO probably sounded like a good idea to W.Gates,
but it took me half an hour to get anywhere near finding out what that
'1' meant. When I did, it was (guess): 'A floating point
exception occurred in the user process. Current transaction is
canceled.' !!!
Can anyone please tell me what exactly might be causing the error?
Graham Rounce
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Aug 20, 2007
sql server 2000 sp4 build 2184runs stats with maintenance plansp_msforeachtablestored procedure updating full stats for each table and the resultsare identicalA floating point exception occurred in the user process. Currenttransaction is canceled.all pointers are to move to latest service packAny pointers on how to avoid this errorThanks for your timeMassa
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Jun 13, 2006
I am trying to run "select * from <table> where <columnname> = 0.0" inquery analyzer<columnname> is a floatI get the following error:Server: Msg 3628, Level 16, State 1, Line 1A floating point exception occurred in the user process. Currenttransaction is canceled.I get the same error when I use the float <columnname> through anapplicationI have tried upgrading to SP4, without any luck - still get the errormessage.Any help would indeed be appreciated.Thanks -AH
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Jul 20, 2005
We get the following error message."a floating point exception occured in the user process. currenttransaction is cancelled".this message comes when trying to excute a stored procedure. Thisexception is unpredictable.OS : Windows 2000 (SP3)Version: SQL server 2000 (SP3).
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Jul 23, 2005
Hi,I'm running SQL Server Version 8.00.194 on Windows 2000.I am am running this query:select TOP 2000TheoVolImpliedfrom OptionTradeswhere ReutersSymbol = 'IBM.N'and TheoVolImplied > 0.0TheoVolImplied is of type float, precision 15, length 8.When I run this query I get this error:Server: Msg 3628, Level 16, State 1, Line 1A floating point exception occurred in the user process. Currenttransaction is canceled.If I run this query:select TOP 2000TheoVolImpliedfrom OptionTradeswhere TheoVolImplied > 0.0It works fine with no problems.If I run this query:select TOP 2000TheoVolImpliedfrom OptionTradeswhere ReutersSymbol = 'IBM.N'It works fine with no problems.Anyone have any ideas about what might be wrong?
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Feb 22, 2007
I've got a price in euro as a string, which I can easily cast to a numeric SSIS data type e.g. R4, R8, DECIMAL, NUMERIC. And I've got the dollar/euro exchange rate stored in an SSIS variable of type DOUBLE, set to 1.28 for testing purposes. I want to multiply the two values and return the (dollar) result, rounded (not truncated) to 2 decimal places, as a string.
Here are some experiments I did in an SSIS expression editor:
(DT_WSTR, 10) (1.28 * 31.10) evaluates to "39.8080"
(DT_WSTR, 10) (1.28 * (DT_R8) "31.10") evaluates to "39.808"
(DT_WSTR, 10) (1.28 * (DT_DECIMAL, 0) "31.10") evaluates to "39.68"
(DT_WSTR, 10) (1.28 * (DT_DECIMAL, 1) "31.10") evaluates to "39.808"
(DT_WSTR, 10) (1.28 * (DT_DECIMAL, 2) "31.10") evaluates to "39.8080"
(DT_WSTR, 10) (1.28 * (DT_DECIMAL, 3) "31.10") evaluates to "39.80800"
Of course, what I really want is "39.81", so I went on:
(DT_WSTR, 10) ((DT_DECIMAL, 0) (1.28 * (DT_R8) "31.10")) evaluates to "39"
(DT_WSTR, 10) ((DT_DECIMAL, 1) (1.28 * (DT_R8) "31.10")) evaluates to "39.8"
This looks promising! But:
(DT_WSTR, 10) ((DT_DECIMAL, 2) (1.28 * (DT_R8) "31.10")) evaluates to "39.8"
(DT_WSTR, 10) ((DT_DECIMAL, 3) (1.28 * (DT_R8) "31.10")) evaluates to "39.808"
Argh... How does one get a floating point value rounded to 2 decimal places???
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Mar 26, 2008
Hello all,
First off, I appreciate the time that those of you reading and responding to this request are offering. My quesiton is a theoretical and hopefully simple one, and yet I have been unable to find an answer to it on other searches or sources.
Here's the situation. I am working with SQL Server 2005 on a Windows Server 2003 machine. I have a series of databases, all of which are in Full recovery mode, using a backup device for the full database backups and a separate device for the log backups. The full backups are run every four days during non-business hours. The log backups are run every half hour.
Last week, one of my coworkers found that some rarely-used data was unavailable, and wanted to restore a database to a point in time where the data was available. He told me that point in time was some time back in November.
To accomplish this, I restored the database (in a separate database, as to not overwrite my production database) using the Point in Time Recovery option. I selected November from the "To a point in time" window (I should note that this window is always grey, never white like most active windows, it seems), and the full database backup and the subsequent logs all became available in the "Select the backup sets to restore" window.
I then tried a bevy of different options from the "Options" screen. However, every restore succeeds (ie: it doesn't error out), but seems to be bringing the database back to a current point in time. It's never actually going back to the point in time I specify.
My questions are as follows:
a) Is it possible to do a point in time recovery to a point in time BEFORE the last full database backup?
b) If so, what options would you recommend I use? (ie: "Overwrite the existing database", restore with recovery, etc etc).
I again appreciate any and all advice I receive, and I look forward to hearing from anyone and everyone on this topic. Thank you.
Ryan
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Sep 6, 2006
for example:
SELECT CAST(CAST(getdate() AS datetime) AS float)
how can i convert the return select value to nvarchar????
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Nov 10, 2006
I'm running SQL Server 2005 on a Server 2003 machine serving both our home network as well as a remote site through a point-to-point T1. While file transfer speeds are up to par, the remote site's interaction with SQL Server (Point of sale system) is very slow. After testing I am certain that it has nothing to do with the actual physical machine in place neither is it an issue with the program itself since speeds are as they are supposed to be over the home network lan. It seems that there might be a packet size issue or something of the sort. Has anyone dealt with this before or have any thoughts?
Thanks,
Peter
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May 18, 2007
Hello all. I am trying to do a calculation within an SQL script, however it doesnt seem to be working and i'm a little bit lost. If anyone could shed some light on where i'm going wring it would be much appreciated. The code I have is:
select
EMPLOYEE.EMPLOY_REF AS EDIT_REF,
SV_EMPLOYEE_CURRENT_HOLIDAY.ENTITLEMENT,
SV_EMPLOYEE_CURRENT_HOLIDAY.CARRIED_FWD,
SV_EMPLOYEE_CURRENT_HOLIDAY.TAKEN,
SV_EMPLOYEE_CURRENT_HOLIDAY.REMAINING,
SV_EMPLOYEE_CURRENT_HOLIDAY.SOLD,
SV_EMPLOYEE_CURRENT_HOLIDAY.PURCHASED,
SV_EMPLOYEE_CURRENT_HOLIDAY.ENTITLEMENT + SV_EMPLOYEE_CURRENT_HOLIDAY.SOLD - SV_EMPLOYEE_CURRENT_HOLIDAY.PURCHASED AS TOTAL_ENTITLEMENT
from
EMPLOYEE
left outer join
SV_EMPLOYEE_CURRENT_HOLIDAY
on
EMPLOYEE.EMPLOY_REF = SV_EMPLOYEE_CURRENT_HOLIDAY.EMPLOY_REF
where
EMPLOYEE.EMPLOY_REF = = 027
Incidentaly SV_EMPLOYEE_CURRENT_HOLIDAY is a view which currently exists.
Thanks in advance people.
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Jul 1, 2007
In order to find out if an event is late or not I need to do some time calculations in SQL as a Stored procedure.
I have a DateTime variable called Due
I also have an Allowance variable which is an integer and is an extra allowance for that day and a third variable Now which is set with GETDATE()
If I compare Now to Due I can decide if the task is late or not - but I need to take itno account the Allowance.
I tried :
IF @Due + (@Allowance /24) < @Now ......
However I find that @Allowance/24 always equates to zero so this doesn't work.
I'd appreciate any advice.
Regards
Clive
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Mar 21, 2008
Hello,
I ran into a little problem. My problem is: i need to substract 2 variabeles from 2 different tables in the database
TitleTimes left todayTimes left
My first excercise!15
My second excercise!19
The fields times left are a calculation... the number of times that the admin entered minus a count in the table scores.
Has anyone an idea how i can solve this?
An example excercise would be great!
Thanks in advance
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Jun 5, 2008
I am attempting to construct a SELECT statement which incorporates some variables. The variables begin life as strings (not String objects) looking like :"6/08/2008" and "06/10/2008" for example. The first is a start date which was retrieved using an AJAX calendar object and the second is an end date retrieved in the same manner. My records are all timestamped by MS SQL (2003) including the clock time. I am stumbling on the syntax. "CallStartTime" is the record's timestamp. The "TraversalString" is something else but I am not attacking that yet. Can anyone make a suggestion or two?
SELECT count(*)FROM RealTime WHERE CallStartTime >= '@starttime' AND CallStartTime <= '@endtime' AND TraversalString LIKE '%1.0%'
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Jun 5, 2006
Timespan = 30 days
Start Date = January 1st
Last Processed Day = NULL
Next Cycle Day = IF(Last Processed Day IS NULL) Start Date + TimeSpan ELSE Last Processed Day + TimeSpan
Is it possible to setup a column to do this from sql?
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Jul 8, 2002
I have a timesheet table and I am having trouble getting a calculation to work correctly. I'd like to subtract the punch-in times from the punch out times for a specific period, such as 1 week, and then add the time together and get the number of minutes worked altogether during that time.
The table is simply
Employee ID (int)
PunchIn (datetime)
PunchOut (datetime)
Thanks for any help.
EL
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Jan 4, 1999
I am trying to do a calculation to find rows which have a date which is 2 days older the the getdate().
i.e Select documentdate from table where documentdate < (getdate() - 2)
Any ideas on how I can perform this operation.
Thanks
Vinny
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Mar 5, 2007
Hi,
I think that I want to want to build a temporary table in a stored procedure that handles multiple calculations.
I'll try and explain and hopefully you can tell me what i want
First i want to populate a list of all dealerstaff.
Code:
Select * From tblDealerstaff
I Then want to calculate the percentage tasks completed. So i find the number of available awards.
Code:
SELECT TOP (100) PERCENT COUNT(NoPerStaff) AS NoAwardsAvailable
FROM dbo.tblIndivAwards
Then i can find the number awards recieved per person.
Code:
SELECT TOP (100) PERCENT COUNT(dbo.tblIndivAwarded.AwardID) AS AwardCount
FROM dbo.tblIndivAwarded INNER JOIN dbo.tblIndivAwards ON dbo.tblIndivAwarded.IndivAwardID = dbo.tblIndivAwards.IndivAwardID
WHERE (dbo.tblIndivAwarded.staffID = @StaffID)
Trying to get my recordset to look like this >>
Fname + Lname + ((iNoAwarded / iNoAvailableAwards) * 100)
I want to know if it's possible to piece all of this calculation into a single stored procedure. I need to do this sort of thing all the time, as i display overviews of the projects i run to the senior managers.
I always do the maths in the ASP, and consequently i can't sort on the calulated totals.
Is this possible, or am i asking too much ?
Thanks in advance, as any help will be greatly recieved.
Regards,
Chris Brown
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Jul 7, 2004
Hi
I sometimes find myself in the situation where I want to insert a row into a table using the following form:
insert table ( <field list> ) select <field list> from .. etc .. Where <conditions>
My question is to do with where one or more of the fields in the select field list are calculations and where I also want to use some/all of these derived fields as Where conditions. [ Eg: only insert if the calculated value is > 0]
I currently either repeat the calculation in the Where clause or move it to a function and use the function call in both places. (I always get a pang of guilt using either option - repeating the calculation feels like bad practice - & using the function twice seems inefficient (does this get optimised?)).
I could get a life & stop worrying - but is there a better/neater way of doing this?
Many thanks.
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Aug 24, 2005
Vikram writes "Hi,
I need some help in date manipulations on SQL server data.
I am required to calculate to see
1. If anyone is absent one day within a 30 day period. if they are then upon their next absence in the same rolling 30 day period they need to be move to step I of disciplinary stage.
this information has to be checked for hundreds of employees.
I tried many ways but am not getting the right results. Moreover upon defaulting they will have to be moved to differnt steps.
Any suggestions will be greatly appreciated.
thanks in advance
Vik"
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Nov 25, 2005
Hello,
I am a student and I have an assignment in for next week and we are having a few problems... below is some code we have created to enter in payment details for a customer....
INSERT into Payments values(Payments_seq.nextval, initcap('&Payment_Method'), '&Amount_Payable',
Date_Due = (select date_of_order from orders where order_no = (date_of_order+7));
I am having trouble with the last line, I want the date due to be calculated from the date the order was made in another table (orders) and I want a week to be added to this so that in the field it will display (date ordered plus 7 days)...
Any help you can give would be great, I've only been using isql plus for about 4 weeks...
Thanks
Pam :)
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May 17, 2006
Users,
My question is about the number of calculation made with my database and my query.
The situation:
Table1: Contains 900 projects
Table2: Contains 13500 timesheets
Table3: Contains 516 Periods
Then there are 3 queries:
Query 1: Calculating the total for the periods
Query 2: Calculating working hours + working hours * total of a period
Query 3: Calculating loancosts of a project.
Query 3 is using 2 and 2 is using 1.
How many calculations are made in total????
Thanks!
Willio
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