I have a DataTable with two DateTime columns: "start_time" and "end_time".Now, I want to add a third column that calculates the difference between the two DateTimes. But I can't seem to figure out how. I've tried to set the .Expression-value to "start_time - end_time", but it says that "-"-operator is not allowed on DateTime.
View 4 RepliesI am trying to build a filter string for my DataView, but I have run into a problem. My underlying DataTable contains values that are formatted when displayed in my DataGridView.For example, if the DataColumn contains 1.52 and the DataGridViewColumn.DefaultCellStyle.Format = "n0" then 2 is displayed.So the user sees 2, then sets the DataView.RowFilter = "DataColumn = 2", and no DataRows are returned. Is there a way to format the DataColumn in the RowFilter string? For example, DataView.RowFilter = "FORMAT(DataColumn, "n0") IN (2, 4)". This filter string should return 3 rows. If not, can LINQ do this?
View 5 RepliesI am trying to write following expression on a datacolumn. But it results in error:Replicate('*', nLevel) + NameWhere: Replicate() is a user defined function (in a module). nLevel and Name are two other columns in same data table.
View 3 RepliesI'm using MySQL to store some numbers. One of the columns in the database is defined as unique, but it does allow multiple NULL-values. That is exactly how I want it.ut when I'm trying to load the data into my strongly typed DataSet, I get a error saying that a constraint fails... I do understand why that happens (several rows with NULL-values in a unique column), but is it a way to keep a DataColumn in vb.net unique, but still allow several rows with NULL-values like in MySQL?
View 2 RepliesI defined a DateTime datacolumn in a datatable dt as [code]]....
View 5 RepliesI'm adding a DateTime DataColumn to a DataTable like this:
Dim colDate As DataColumn = New DataColumn("Date")
colDate.DataType = System.Type.GetType("System.DateTime")
dt.Columns.Add(colDate)
Then when I try to add it to my datatable, if the value is Nothing I get an error saying string was not recognized as a valid DateTime. I'm having trouble getting this to work.
Is there a way to change when an expression in a datacolumn is evaluated?
I'm trying to make a simple total function which sums the values of a particular column in a data grid. Normally the expression is evaluated when I leave from the datagridview, but I wish it to be evaluated when the row is changed.
i read an article about datacolumn.expression property here [URL]. this is really great. but i was just wondering, for my case i want to use my custom function to use in the expression. basically, on my datatable i added an unbound column AGE. when i display records, i just want the age textbox to be populated with the computation of the person's age based on birthdate.
View 7 Repliesdatacolumn expression subtracting dates and taking to datagridview
View 1 RepliesI'm trying to assign some parameters for a stored procedure with some values that are stored in a data table. in the code, I can set the parameter values to the data table, and give a column header or index without issue, but when it tries to execute at runtime it bombs out.the error I get is a variation on "Failed to Convert Parameter Value from a DataColumn to a String" depending on exactly how I try to assign the value.the data types are all correct elsewhere in the code.
my code for this bit is
Try
ConnectionAttempt.Open()
Try
With NewYearCommand_Dates
[code]....
other things I've tried to get this to work are all variations on the .Value=dates bit, such as
.Value=dates(0) (so using column index)
.Value=dates.columns(0) (again using column index)
I've also tried declaring variables, and setting their values to the values in the columns, but the code returns an error saying that "Value of type 'System.Data.DataColumn' cannot be converted to string".I should point out that i'm doing this for 3 tables at once in this sub, 2 of them will only have a single row of data, but the third has an indeterminate number of rows.I'm afraid I don't know what else to do. I'm lead to believe by my mate and my lecturer that this should work, and of course it will work, but the evidence says otherwise.
I have added a column to a Datatable called CallsPerDay which is there to tell me how many telephone calls have been made on a particular day or days.Is there a datacolumn.expression which will allow me to Filter on the day, count the rows and then populate this added column with the result.
View 1 RepliesHow can I get the difference of this two Date time.
(6/21/2011 7:02:53 AM) subtract by (6/21/2011 4:00:00 AM)
the answer should be ---> 03:02:53
I have a two different tables, Table 1 and table 2.
Table 1
-----------
Resource
Start Date
End date
[Code]....
Here I have to match the total hours of each table according to the resource,
then have to find the mismatched data and find difference with that values of mismatched data.
I have a DateTime Picker that I have set Format to "Custom" and CustomFormat to "dd/MM/yyyy HH:mm"
When the user changes the date time it all works fine and update the table no problem.
If the user does not change the date time I get the error[code]...
I need to write a program that calculates and displays the depreciation of a businesses assets.I need the program to read a comma-delimited input file containing the names of multiple assets, their purchase prices, the years of their purchase and the number of years that the assets are expected to be useful.I need to use this straight line depreciation formula- (purchase price / number of years of usefulness) * (current year �purchase year)
View 7 RepliesI'm trying to add the date and time of Today into a Sql-database-field that has the datetype datetime.
[Code]...
the msgbox gives me the following result: 29/01/2011 18:49:21 my sqlException gives me the following error: 102 - Incorrect syntax near '18'. Is it better that i set the datatype to char in my sql database? It's maybe a bit easier? When I do that, can I calculate with these date?
I am fetching DataTime value of a SQL Database, LockDate. Dim diffDate As TimeSpan diffDate = DateTime.Now - LockDate minutes = Convert.ToInt32(diffDate.Minutes) hours = Convert.ToInt32(diffDate.Hours) Minutes value is showing incorrect values.
View 1 RepliesI'm tried creating an analog clock and I realized I was terrible at trig and gave up. So instead I'm just creating a digital clock. I'm having problems getting the alarm to go off. Lemme explain my layout, I have 3 comboboxes. 1 is for the hour, 1 is for the minute and 1 is for am/pm.
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
'The commented out variables are global
[Code]....
I'm working on a project that's going to be deployed via .NET on Windows and via Mono on Linux; the same data needs to be exchangeable between the platforms, including where platform A is Little-Endian and platform B is Big-Endian.Where text is concerned, I know ASCII/Unicode is natively Big-Endian, so there's no problem with that.Where numbers are concerned, I know that byte arrays have to be reversed on Big-Endian platforms to store the data in Little-Endian format.But what exactly is the 64 bit value output from System. Date Time.ToBinary?Is this a number representing the number of seconds elapsed since Jan 1 1970, is this some kind of serialized attribute that outputs some DotNET-recognizable value, or what?Does this byte array need to be handled differently in Big and Little Endian environments?It never hurts to try. In a worst case scenario, you'll learn from it.
View 7 RepliesI have a problem when i am passing negative value to "AddMinutes" function.The problem occurring when i subtract a value from the "00:xx:xx".[code]When it is trying to subtract, it is throwing the "Un-representable DateTime" error.How do I do the subtraction of minutes in this scanerio?
View 3 RepliesI currently receive spreadsheets from clients which include several date fields. Since these are coming from many different sources, the date formats can vary widely (although they will all be US format). It could be "April 19, 2010", "4/19/2010", "2010-04-19", etc. I would very much like to use the DateTime.Parse function rather than having to write my own parsing function--I don't want to have to write out every possible combination of date strings.
The problem is, the DateTime.Parse function includes default values if all values are not supplied. So if the field comes in as "03/2009", since no day was specified, the function will return a datetime equivalent to "3/19/2009" (today's day along with the values given). I cannot use this. If a client provides a date that is incomplete, my program must produce an error, not fill in default values for them. Is there a way to tell DateTime.Parse not to use default values? Or perhaps there's another function that can parse multiple string formats into DateTime type without using defaults?
I am using VB.net 2003 application program. I am trying to do a select statement whereby I'm searching between 2 datetime values that are being stored as datetime. records are stored inside Access. For example, I am searching between 2 datetime:
StartTime = 2/23/2009 9:00:00 AM
EndTime = 2/23/2009 11:30:00 AM
So I need to find all the records in between 9:00 AM and 11:30 AM on 2/23/2009.
strSQL = "select OrderID from Orders Where OrderDate >= ('" & StartTime & "') AND OrderDate <= ('" & EndTime & "') "
but i got the error showing below:
An unhandled exception of type 'System.Data.OleDb.OleDBException' occurred in system.data.dll
strSQL = "select OrderID from Orders Where OrderDate >= DATEVALUE('" & StartTime & "') AND OrderDate <= DATEVALUE('" & EndTime & "') "
But when I use DATEVALUE, it takes the date from the string and set time as midnight (00:00:00). So it returns no records between 9:00 AM and 11:30 AM on 2/23/2009, but I can see there are records. [Code]
strSQL = "select OrderID from Orders Where OrderDate >= TimeValue('" & StartTime & "') AND OrderDate <= TimeValue('" & EndTime & "') "
And when I use TimeValue, it returns the time from the string and set date as jan 1st. so it returns no records between 9:00 AM and 11:30 AM on 2/23/2009, but I can see there are records. [Code]
but none of the codes above is returning records between 9:00 AM and 11:30 AM on 2/23/2009, but I can see there are records. i searched and found all those examples. but that didn't work. Is there anyway i can search between 2 datetime values. i need to find all the records that lies between that time period (for example: between 9:00 AM and 11:30 AM on 2/23/2009).
I'm using Microsoft Visual Basic 2010 Express...i have a form that has multiple checkedlistbox controls with multiple checkboxes inside. I'm trying to simplify unchecking everyhing. There may be an easier way to do it but here is the code that I'm trying to use.
Private Sub btnUncheck_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUncheck.Click
Private Sub btnUncheck_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUncheck.Click
Dim i As Integer
Dim num As Integer
[code]....
how do I pass the values of my array into my expression that sets the state of the check box (me.ckarray.setitemcheckstate(i,false)?I can see that the values are correct when I uncomment the MsgBox(ckArray(num)). It cycles through all the array values then exits.
I have a date value (e.g. 2011-04-11 07:45:00.000) which I am pulling from my database (via Entity Framework). I need to pull out only the hour from the original date value (e.g. 07:45:00), get the current time, and then subtract the current time from the database time value. In pseudo-code, I'm looking to do something like this:
Dim my_date as DateTime = from_db ' This is the value pulled from the database.Dim this_date as DateTime = Date.Now ' This is pulled via a VB.NET function.Dim my_hour = my_date_but_only_hours ' Somehow, I need to strip the date off the my_date Dim this_hour = this_date_but_only_hours ' Same as line above.Dim hour_difference = my_hour - this_hour Response.Write("There are " & hour_difference & " hours left before the time runs out.")
I would like to be able to display null values in a datetime picker control. I am using one datetime picker control for both datadisplay and data entry. when I load the data from the database and if there is no date then the datetime picker control must be blank.
View 3 RepliesI have been dabbling in VB before and i played around wiht linq to sql back then but im wondering what i should go with here.I need to have a list of people.. They should all have their own id nr.
The people in the list are supposed to keep a record of values changing over time with a datetime stamp. (In my case its numbers from a test outcome of blood)You have to be able to add people and delete people. All records will be deleted too.A Chart will read information from the records and display changes over time in chart.I was thinking of doing it with linq to sql and i was kinda aiming at Creating datatables with id names from the script
Havent found a way of creating datatables from a script though..I was hoping for a solution like that.. And i was hoping id be able to search databasetable names.
I'm trying to create a Windows form application which uses a few data grid views to pull data back from a SQL Server database. I've managed to get the data back okay from the tables but what I want to do is filter that data dynamically based on values input by the user from a combo box and a date time picker. Each of the data grids display production data for a machine but the combo box and date time picker will allow the data to be filtered by shift and date respectively - how to I pass the values of these to the SQL query returning the data?
View 4 RepliesI am trying the following to select a long date, but becase the value is stored in SQL database as DateTime I am unable to return any results unless minutes and seconds match perfectly...I then tried to use 2 calendars and have the same issue with the DateTime format..
CODE:
Dim re As New Regex("((?<field>[^"",
]+)|""(?<field>([^""]|"""")+)"")((?<rowbreak>,
|
|
|$)|,)")
[Code] .....
Now it puts all the data in the correct columns but there's just a comma in the empty columns.
lambda - vb.net lamba expression to select all values between lower and upper values plus the next lower and upper value. I need some help with a lamda expression to get a subset of range of values. I have a lower and upper value, and getting everything between them seems easy enough, but I also need the next lower and higher value to be included. I can do each of these separately, but would like to do it in one shot if possible.
The range I need the subset from has 150 values. A small example would look like:
{8.206,8.206,8.201,8.196,8.193,8.192,8.189,8.174,8.171,8.171,8.166,8.163,8.157,8.154,8.153,8.14,8.131}
My lower value is: 8.16
My upper value is: 8.17
I need to get back: {8.171,8.171,8.166,8.163,8.157}