Using Datatables As Datasource For Comboboxes?
Apr 20, 2010
I use single column datatables in combination with the .DisplayMember and .DataSource property to populate comboboxes. Data for these datatables I get from a MySQL database. All this is working fine, but I noticed some behavior for which I can't find an explanation, and am not sure of if it can be prevented somehow.Some of the datatables are used for different comboboxes on different tabs. The behavior found is that with comboboxes that have the same datatable as datasource. If I select an item in 1 combobox, the others automatically select the same item.
-Is this normal, because I couldn't find any documentation on this behavior?
-Can it be prevented, and if so how?
I could use a for next loop and manually add each item to the combobox, but using .DataSource is so much cleaner and more efficient.
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Oct 28, 2011
I have a form with 4 comboboxes and a button. The first combobox is enabled, but the rest of the controls are disabled. When the form is opened I fill the first combobox (cbxMethod) with a datatable. When the user selects something in cbxMethod the next combobox (cbxStudy) will be filled and so on. When the last combobox (cbxAnalyte) has a selected value I want to enable the button and give it focus so the user can move forward with the program. I basically want to force the user to move from one combobox to the other, until all are filled.I am currently using the SelectionValueChange event, but this event only fires when the user changes the value with their mouse or hits the Enter key, not when the user hits the Tab key.
Public Class frmCalculatedAnalyte
Private cv_dt As New DataTable
Public Sub New()
[code]....
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Oct 22, 2009
Visual Studio 2008 Express Edition.I have a have a DataSet, created from (part of a) Access database. I have tow tables in it (say A and B). When I change something in table A, I need to get data from table B to complete table A.My approach was to use the RowChanged event inside a (Partial) Class of table A. For that to work however table B needs to be shared. (I don't like to refer to an instance.) I got it to work by changing the DataSets designer code, but don't want to do it all over again when the code is regenerated for some reason. So: would there be any way to have these tables shared by default?
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Apr 21, 2009
I have two combo boxesthat use the same collection for their datasource. The data member and value member are also the same properties. When the form loads, and I select an item in one of the combo boxes, the same item is then selected in the other combo box. I want the combo boxes to work separately. Do I need to have two different collections, even though they would have the same data in them?
cboInboardKnife.DataSource = cKnives
cboInboardKnife.DisplayMember =
"Name"
cboInboardKnife.ValueMember =
"ToolID"
cboOutboardKnife.DataSource = cKnives
cboOutboardKnife.DisplayMember =
"Name"
cboOutboardKnife.ValueMember =
"ToolID"
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Apr 9, 2009
I want to maintain a list of potential ComboBox values over multiple executions of my program, and to use that list as the DataSource on multiple ComboBoxes. I also want changes made to the DataSource to propagate over all of the ComboBoxes already existing in the application.
Can someone recommend what type of object I should use as my DataSource, as My.Settings objects don't seem to support generic list objects.
Also, along with that recommendation, can I also ask for suggestions as to how to propagate the updates of the collection to all ComboBoxes? I would imagine I need a collection type which raises events when its contents change, but I can't think of any, and in any case do not know which are compatible with My.Settings.
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Jan 21, 2011
I was just writing a windows application that populates three comboboxes from the same datasource. My datasource is a datatable. The way i populate the comboboxes is by repeating the following code for each of the comboboxes:
'populate 1st combobox
cbx1.DataSource = table
cbx1.DisplayMember = "someColumn"
cbx1.ValueMember = "anotherColumn"
cbx1.SelectedIndex = Indx
[CODE]...
When the application is run, and I select an item from the dropdown list of, say, cbx1, my choice is reflected in cbx2 and cbx3 as well. I find this behaviour strange and will be grateful if anybody could explain what is going on here behind the scenes. On a side note, I've been able to circumvent this problem by modifying my code as shown below, but would still like to have an explanation for this seemingly strange behaviour.
'populate 1st combobox
Dim t1 as datatable = table.Copy
cbx1.DataSource = t1
cbx1.DisplayMember = "someColumn"
cbx1.ValueMember = "anotherColumn"
cbx1.SelectedIndex = Indx
[CODE]...
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Jun 1, 2012
I'm having a hard time joining 2 datatables and have the joined datatable as result. First datatable (labels) holds data including a printerid. Second datatable (printers) holds printer references (id > unc). I would like to have as endresult (joined) a datatable with all data from the first datatable with the field (unc) of the second datatable. [Code]
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Apr 24, 2012
this is a subset of a previously posted problem, I have narrowed down my issue and am reposting a question from this thread: [URL] I have apparently confused the compiler by renaming some comboboxes in Visual Basic .net express? (See relevant code below) I think the confusion is in who should handle what, with two routines named with variations of ComboBox1 and one handling the other ( it confuses me just trying to interpret it mentally):
[Code]...
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Jan 30, 2011
I use vb.net and windows form and sqlserver
I added Data Source(Microsoft SQL Server (SqlClient)) to my project. and now I need to change it to ODBC Data Source .
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Nov 11, 2011
I'm trying to the contents of a datatable to a datatable thats allready in my form using the openfiledialog.[code]...
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Apr 12, 2010
I'm trying to create a program that will merge two data tables (one from a database on a network drive, the other is found in a database on the local machine). Each datatable is identical in structure, only (maybe) differs in content. The structure has a primary key, dateCreated, and dateLastEdited fields (plus other fields). I would like to merge down from the network to the local database. If the primary key does not exist on the local db but does on the network, copy from the network db to the local table. If it does exist, check the dateLastEdited column and copy the latest row to the local table.
How would i set up the code to do this? Any assistance would be great.
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Jan 23, 2012
How to intersect two dataTables in vb.net 2.0? I want to get common rows in two datatables and add it in third datatable.
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May 20, 2012
I need to marge two datatables with condition. I have a datatable where the data comes from a local XML Database and another datatable where the data comes from a remote SQL Server. If any update made in the remote datatable I need to update/merge with the local datatable. Here is what I have so far:
Public Sub MargeTwoTable()
Dim SQL As String = ""
Dim RemoteTable As New DataTable
Dim LocalTable As DataTable
[code]....
In this code data comes from the remote database which updates a date getter then the local database . Both tables have "ID" as the primary key. The code is working well, but the problem is that when more than 1000 records are updated this function takes too long using loops.
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May 28, 2012
I have two datatables which I intends to bind them to Gridview. But I need bit of the first dt and bit from second dt.
Second table has only one row that represents to every row in the same column in first table.
There is no primary key or relationship between two tables though.
For example,
I tried datatable.merge though. Didn't produce the last table i want.
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Jun 7, 2012
I have a Main Table that contains all the distinct values in a DataTable.DataColumn. also have a Child Table that contains distinct values created by the user.I want to merge the Child Table DataRows that match on the Value column with theMain Table DataRows to create the New Table (shown below).I want to preserve the values in the Selected column of the Child Table.Here is my problem, if I use the DataTable.Merge method the DataRow that contains "888" in the Child Table is added to the New Table, but it doesn't contain a RowState = Added, thus I can't filter for added rows to remove them.
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Jun 10, 2010
I am using VB Express 2008 and SQL Server Express 2008.I have one DataGridView on a Windows Form, which I am attempting to populate from two datatables. Both tables are identical in structure, but with data from two different dates. The respective SELECT statements are identical, except for the date; one calls for yesterday, one for today. I need a seperate Sum column from each table.I've tried to JOIN, UNION, and MERGE the tables, but that gives me all the data consecutively and I saw no way to seperate the days. I'm able to add DataColumns, and sum the fields with an expression, but is it possible to create DGV columns and bind them to the seperate DataTable columns? [code]
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Mar 19, 2012
I am stuck with an issue.I have two datatables, with the same table structure, i need to select data from table1 such that the records arent existing in table2is it possible to do this in vb.net? if yes then how?
Table1(AAno,Agencyname,location)
Table2(AAno,Agencyname,location)
Criteria:Select AAno,Agencyname,location from table1,table2 where table1.AAno<>table2.AAno
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Oct 12, 2011
I'm stumped trying to do an equivalent SQL statement in VB 2010 working with two DataTables, & am hoping someone could point me in the right dirction.I currently have two data tables with three fields each :- A, B, C. The data in field A is the same in both tables & could be used to join the two tables.How could I input data into a third data table having data from both primary tables ? Something along the lines of the following SQL code.[code]
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Jan 18, 2012
I have a datatable with a yes/no checkbox in it and when I filter my datasource it loads form2. Right now I'm using this code to have a label's color as green if it's checked and red if it isn't:
Private Sub Customers2BindingSource_CurrentChanged(sender As Object, e As System.EventArgs) Handles Customers2BindingSource.CurrentChanged
If ActiveCheckBox.Checked = True Then
Label1.Text = "Active"
[code].....
That works when I do something like bindingsource.movenext because it's in the bindingsource_currentchanged event, but when I try adding that to the form_load it's automatically set to Inactive, color red. I figured it's because is set to checked = false, but what event do I use to make this work when the form loads?
What's the value of a checked checkbox for the update/delete/insert commands? Like dates are DateDateTimePicker.Value.Date. Is it something like this?
.AddWithValue("@Active", ActiveCheckBox.Checked)
I don't use checkboxes to often.
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Apr 27, 2012
I've seen several posts on the subject, but none seem to answer this particular dilemma. I have two datatables that I obtained by querying two separate servers.[code]
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Mar 23, 2009
I am trying to compare two datatables and generate a resultant datatable of rows that do not match based on customer number. The main table "Customers" contains all customers that have been placed in our system. I am trying to generate a table of customers, "dtResults," that we have not ever generated an invoice from a table called "CurrentCust".I would like someone to look at the attached code and see how I can handle the 'InvalidCastException was unhandled', 'Unable to cast object of type 'System.String' to type 'CustomerDataTable' error. Error occurs at line 43.
1
Option Explicit On
2
Option Strict Off
[code]....
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Jun 11, 2012
using VB.net 2010 using DataAdapter and DataTables I'm trying to merge two datatables together and update a database with the results if I use the following code it works (though not ideal):
For Each tRow As DataRow In excelDt.Rows
accessDt.Rows.Add(tRow.Item(0))
Next
however if I use the following I don't get a error, it just doesn't update:
accessDt.Merge(excelDt)
accessDt.AcceptChanges()
For ease here I named the DataTables to describe where they are coming from. accessDt is a empty DataTable (to start) from a Temp Access database table with 1 or more columns in it and excelDt is a DataTable created from a Excel Worksheet with the same columns (same order as well) as the Access Table. Basically just trying to get the data from Excel into Access. They are using the same update command just swapping out which method is commented out. I have checked and accessDt does have the data in it before the Update is called using both methods.
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Jun 28, 2010
I am in the process of revising code to use TVP to send data from our VB.NET app to the SQL 2008 DB and try to keep all the writes atomic.[url]...
I am in the process of creating all the in-code datatables to be sent to the SQL stored procedure
However, I will have to create these datatables and datacolumns (then add the columns to the tables) repeatedly for multiple tables.
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Jun 14, 2011
I have a sequence that reads the selected Excel-file and displays the first row of the columns in the Excel. (The first Excel row has the column names)
Dim cmd As OleDbCommand = New OleDbCommand("select * from [" & tableName & "$]", MyConnection)
Dim dr As System.Data.IDataReader
Dim dt As New System.Data.DataTable
dr = cmd.ExecuteReader
dt.Load(dr)
With the above code I can read the the first rows of the Excel table and choose the names of the columns I like to keep. (By populating the first row to my ComboBoxes)
So, at the moment my DataTable dt has all the table header names but on the first row. And as the header names it has F1, F2, F3, ... F13.
How can I make my new DataTable dt2 take the first row of dt and make it the column names row? How can I choose which columns do I want to transfer from dt to dt2 ???
I have tried the following (Doesn't work):
Dim dt2 As System.Data.DataTable
dt2 = dt.Copy.Columns("F1", "F2", "F3", "F4")
DataGridView1.DataSource = dt2
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Dec 2, 2010
Their system executes a DB query everytime they select something, causing performance issues. So I thought that I would read the superset of data into a datatable, and then whenever they want subsets, simply run against the datatable. I've done some testing and the performance difference is HUGE.The problem is how the screen paints on postbacks. The screen will temporarily go blank then the data will appear as expected. Of course, they don't want the blanking of the screen each time they select a subset of data.
I am currently using a repeater to handle the display of data due to the nature of what they want to display. A datagrid might be a good alternative for sorting functions, but I think it would still blank the screen when it data binds.How do I go about filling the repeater without blanking the screen? Is it even p[ossible? Logically I would think not but I don't have the experience. Or perhaps I can fill a datagrid without blanking the screen on the postback?I'd rather not have to go out to the database every time, but if that's the way to go then I can live with that.
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Jan 7, 2010
I am working on a mdi project and I have a few different xml files that I need to read in and I would really like to use multiple datatables, but only one dataset. I have always struggled to get a datatable.readxml(filename) call to work without an invalidoperationexception b/c of the schema stuff. I don't understand it very well and in the past my workaround was just to make another dataset. I am trying to avoid doing that from now on. I have written a routine called readxml which will take a xml file name, xml schema file name, and a datatable name and return to you a populated datatable..but I can't get it to work.
Here is my call to the read xml method (comes from my main mdi form class during form load)
Dim dt As DataTable = globals.xml.readxml("SqlConnectionString.xml", "SqlConnectionString.xsd", "sqlConnection")
Here is my readxml routine, I will post two versions of what I tried attempt #1: use a string of raw xml and a xmlreader
[CODE]...
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May 4, 2011
I just discovered that ODBC and OLEDB drivers I need to use do not support Access nested queryDefs. The database I was given is full of many layers of nested queryDefs. Is there any way I can build the tables in memory from simple query defs and then use those tables in subsequent querys?
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Mar 10, 2010
How To Join Two Datatables From Different Datasets (With One Commn Column) ???
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Jun 22, 2010
I have an access 2007 Database where I store several different "Jobs" such as repair job, data recovery job etc.
At the min I have a form where the user can view a customer's related jobs either by type, or all jobs related to the customer. I'm trying to do this by adding each job type to it's own DataTable, then merging the DataTables into one.
Private Sub rdoShowAllJobs_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles rdoShowAllJobs.CheckedChanged
'####################### Procedure Level Constants and Variables ###########################
' Dim dtDataRecoveryJobs As New DataTable
[Code]....
What I want is for the first column, ID, to contain the primary key from each table, but when the code runs it adds each primary key column from the tables to the end of the AllJobs DataTable! Am I trying to do something impossible here or is there a way around this?
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Nov 25, 2010
I am trying to create a stock scanner which allows users to filter stocks based on multiple criteria that they select. Like the following example with 2 criteria:
Criteria 1 Filtered Result: StockA, StockB, StockC, StockD
Criteria 2 Filtered Result: Stock B, Stock C, StockE, StockF
SCANNER RESULT: Stock B, StockC (ideally this result would be displayed in a GridView)
[code]......
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