Test If A String Exists In A Column In A DataTable?
Sep 15, 2011
I have two tables, dt & dtResults.dt contains 3 columns named: vchInstrumentAnalyteID, bintAnalyteCodeID, & vchAnalyteCode dtResults contains several columns including the columns in dt
I want to get vchInstrumentAnalyteID from the first row in dt and test if it exists in the vchInstrumentAnalyteID column in dtResults. If it exists, I want to use that value from dt to filter rows in dtResults and fill all the filtered rows with data from that row in dt. Then loop to the next row in dt.
I have this code, which is close to what I need, but I can't get it working.
' put analyte data in results table
For Each drA As DataRow In dt.Rows
If
[Code]....
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Oct 15, 2008
I have a datagridview which is populated from a datatable. This works fine. But if i run it more then once i get a column name "example" already belongs to this datatable. Ive tried everything to clear all the columns of the datatable and the gridview but still the same
[Code]...
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Nov 8, 2011
I am using VB.NET and ADO 4.0. Given that I have a string containing a reference to a table.column, can I use the content of the string in a command? [code] I got to the point where I can use the string contents as "reference", it seemed to obvious but [strName] does the trick, partially.When I debug bookableday.room1 remains 0 whilst it should show 6. There might be a conversion issue because the debugger shows me "6" i.s.o. 6 . this is the actual code: [code]
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Mar 24, 2011
I have a database (access) and a listbox which is databound to it etc, and controls the currently selected row in the database.
And i want to check a columns value from the selected row via code, how can i do it? None of the examples on google are recent or for vb.
The column i want to get the value from is
Coulmn name = Related
Column number = 15
The value will be used in a filter so needs to be returned as a string
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Mar 6, 2009
I'm reading an XML file that looks like this[cod]...
The resulting List(Of Vehicle) is then bound to an ASP.NET ListView control where the data is rendered. All goes well if all the desired nodes are present. For example, the Mileage node is conditional and is absent sometimes. Whenever the node isn't present I get a "Sequence contains no elements" error.
I've tried everything I know to get things working properly. Is there a way to test if an XElement exists?
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Dec 22, 2010
I have a method which tests for the existence of a file prior to carrying out some manipulation of file content as follows:
[Code]...
The idea is that if the file does not exist, then the file is generated by calls to the NLog logger instance, at which point the file is created and the specified header info is inserted. The method works fine from the application itself, however I have a simple NUnit test which implements a test method to verify that the file is created and populated as expected. When I step through with the debugger, I find that '_logPath' is set to:
D:Documents and SettingsTE602510Local SettingsTemp
unit20ShadowCopyCache4288_634286300896838506Tests_-1937845265assemblydl37cdfe61aaa18c98d_f0a1cb01logs2010-12-22.log
Unfortunately, despite the fact that the file DOES exist, the call to File.Exists returns false. From earlier viewing of the config path the above path would appear to be correct for these NUnit tests. Does anybody have a clue what is happening here and what I need to do to get the desired result? The pathname to the log file as per the XP file system is:D:Documents and SettingsTE602510My Documents_VSSWorkAreaPsalertsIpTestsinDebuglogs
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Jun 28, 2009
how can i test if datable exists?
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Feb 7, 2011
I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING. The DataTable is NOT populated by a SQL statement, so no order by. If I do
[Code]...
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Mar 5, 2009
I need to sort a DataTable or DataGridView by a column that is a string value, but with null/empty values at the BOTTOM when sorting ASCENDING.The DataTable is NOT populated by a SQL statement, so no order by.If I doDataGridView1.Sort(New RowComparer(System.ComponentModel.ListSortDirection.Ascending))then it throws an exception, saying that the DataGridView is DataBound, which is correct, but doesn't help me, and I want to keep it databound.
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Sep 25, 2010
I don't understand the error, Argument not specified for parameter 'test' of 'Public Shared Function TestThis(test As String)'.
Partial Public Class Form1
Shared Sub ReceiveCallback(ByVal ar As IAsyncResult)
Form1.Invoke(TestThis, New Object(){"test"}) 'error
[code].....
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Mar 15, 2009
I have a datatable which has 5 column. It is possible to copy only its 2 column in and save it into new datatable.I used this code but it copies all the 5 column
Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj).CopyToDataTable
i used this one but it is not supported
Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj.item("Column1"), obj.item("Column2")).CopyToDataTable
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Jul 22, 2010
I was asked this question recently in a test, which I didn't pass. For the life of me, I couldn't spot what the problem was. It's probably something really obvious as well, but even a colleague of mine couldn't spot it either. The best I could come up with was issues with bottlenecks and naming inconsistencies of parameters! I blame it on the fact I've not done any vb.net for years, I've been doing C# mostly these days
[Code]...
The question: This function, although it will successfully sort a datatable, has a major problem with it.What is the problem? Re-write the function in either C# or VB.Net using LINQ.
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Sep 13, 2009
I have a windows service which fetches data from various datasources and build a XML file and send it to a webservice. For example first I will get customer details from Oracle Database and build the XML file and then the SQL Server database and build the customer details XML. I am planning to use the same function below to build the customer object irrespective of what the datasource is. But dr("age") column is not available in SQLserver datbase How can I check if a column exists or not.[code]
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Sep 3, 2010
Why am I getting this error, I know there is data there, the code I am using is:
Dim iMaxFields As Integer = oDataReader.FieldCount - 1
Do
sLine = ""
For iColCounter = 0 To iMaxFields
sColOutput = oDataReader.Item([iColCounter]).ToString()
sLine = sLine & sColOutput
[Code] .....
Basically I just want these details put into a HTML table.
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Nov 4, 2009
I am doin a library management project for my college using vb.net and Ms Access as database. I am getting a error No data exists for the row/column. wen i try to select a value in 1st combobox . The first 3 values are working perfectly wen i click on 4th i get error heres da code
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
[CODE].......................
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Dec 31, 2009
I want to insert a value from loop in datarow so before entering value in datarow, i want to check that a perticular column NAME exist in table or not...please tell me how can i check it. (vb.net preferred).
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Nov 14, 2008
I have a function in VS2008 VB.NET that creates a dataset and reads field values from that were loaded from a SQL Server 2008 database tables. The tables are from varied sources and in some cases particular column/field names are different. Some use a long name; others use a short name. I need to determine whether a short name or a long name is being used.Pseudo code:If row("ShortName") Exists then ReadDataFrom r("ShortName").ToStringElse ReadDataFrom r("LongName").ToStringEnd If
How would I determine if a particular column name exist in a dataset or datarow?
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Jan 22, 2010
I am creating a program which searches saved .htm files for the source codes. I get the source code and do manipulation on the code to pull the values I need into a datagridview.
Is there anyway to search a datagridview column to see if a value exists first, so no duplicate rows of data will be added? I was thinking of making access table and linking the datagridview to it, but i'm not sure how to set the database links up with code (other than the gui), and then still search the column so I don't put in duplicate rows.So far, I have only come up with the way to add the data row by row...
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim IMsku As String
Dim IMskuitna As String
[code].....
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Jan 20, 2010
I'm trying to do an if statement to determine whether a value entered in a text box exists within a column..
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Feb 5, 2012
I have a data table, i want to add a new column on that table, the data in that new column will depend in the data from another column. Now i can think of two ways to accomplish this, first is loop through the whole table and do the statements to get my new columns appropriate data. the second approach would be to give the new column an expression, then convert the table to xml (to remove the expression) then convert the xml string back to datatable.
Now, is there any other way around this? what could be the most optimized way in solving this task?
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Oct 27, 2011
After Filling a DataTable in GridView's DataSource . A column with check box Type appears but it created as read only column and I can't enable it or make it editable... even i tried .readonly = false and still can't be edited
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Oct 18, 2011
I am working on finishing up a mvc 3 vb.net app... I have to parse about 2000 entries in a database and get the string value to the right of a " : " delimiter from one of the columns... Everything to the left I am not worried about but I need the value that is to the right of the colon for that item.. I have more issues involving needing to select string characters to the right or left of a delimiter... But if someone can show me how to achieve the above I can figure out the rest from there...
a example of the string is Jackson Smokehouse Fish Food:John Jacob JinggleHimer Schmit I would want to eliminate the first part of the string or just select the second part and put it in a variable for later processing...
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May 31, 2010
I have brought an array in from a range in excel. This works fine. Through debugging i can see the values are brought in correctly.
Issue is I want to see if a string exists within that array (or cells).
I have tried lots of things and pretty much mutilated my code but here it is:
Code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim folderinfo As String
[Code].....
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Dec 30, 2010
I have a string say, str = "system.Int16" I want to add a column in DataTable say, dt = new DataTable()I want DataType for that column as per 'str', i.e. System.Int16 Then How to? dt.Columns.Add("MyColumn", ...)
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Aug 13, 2011
I am building an application to update a database.I have a Map table where row 0 holds the target table field name Row 1 holds an update value or Source table Column name Row 2 holds a Where condition eg
Map: CustNo CustName Val1 Val2
Update: 25
Where: =[CustNo] > [Fld14]
In this example I am going to update the Target Table Field 'Val1' to 25 where the Target Table Rows have Field 'Val1' data > 14 AND Target Table Field 'CustNo' = the Source Table Field 'CustNo' AND the Target Table Field 'Val1' > the Source Table Field 'Fld14' Where I am stuck is I at the moment is wondering how I should convert the strings into test conditions as I iterate the Target Table eg Say my test string is stTest and it holds " = 25" For each dr as datarow in dtTarget
some code
... stFld = "Val1"
if dr(stFld) { convert stTest into literal '=' and then 25}
... do something the only way I can think is to build up a series of test cases like:
Select stOp
Case stOp = "="
Case stOp = "<>"
etc.
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Aug 15, 2011
Reverentjim kindly gave me this code the other day that worked well. There are two more things i am trying to do but cant get my head around it.
1) I want to be able to extract the text after the second and before the period e.g. profile
2) if exists, I want to change the text to lower after the period
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Jun 24, 2010
I'm looking for some code in .net to allow me to test an xml file to determine if it is well-formed. I am not validating the file against a schema at this point in my code, just testing that it conforms to xml specification for being well formed.
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Nov 24, 2010
I bought acheap USB barcode reader so i could play around with some hypothetical situations. I've managed to get a good chunk of stuff worked out, and had alot of fun along the way. But i thought to myself what if the same tag is passed back along the chain due to production defects and requires remaking.
When it returns to the station to be retagged complete, how do i set the condition for it to search to see if the bar code string already exists in the database prior to either adding a new row (if if returns negative) or to append a cell in the table if the search retuens a positive result.
[Code]...
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Jan 7, 2010
I need to check if a webpage exists if it does whether a certain string exists anywhere on the page. Preferably I'd like to do this without a webbrowser control, so that images don't have to be downloaded and it doesn't have to be rendered.
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Nov 6, 2010
Can't add a new column for DataTable
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