'DBNull' When Searching A DataGrid?
Dec 21, 2011
I'm writing a program for my friend as a gift. He's a movie lover, and has this Excel spreadsheet with all the movies he's watched in it. I converted the spreadsheet to an Access database,then used that database in my program. I've been going by the example in my textbook (Programming with Microsoft Visual Basic by Diane Zak), and everything been working until I put in a "Find Movie Title" button. I want to be able to search the column "Movie Title" for a title input by the user (whether it's the whole title or just a few characters)Here's the code:
Private
Sub btnFindTitle_Click(ByVal
sender As
Object,[code].....
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Feb 24, 2010
I have a populated datagrid that has some fields that are needed for calculation in my app. In the dataset they are set to Allow DBNull False because I can't have a DBNull in my calculation for obvious reasons. I have found answers to incorrect data entry and blank fields in these critical fields (see code block below), but they only work if some data is entered somewhere in the new record, even if I populate the field with default values other than <DBNull> on adding a new row. If a user doesn't add any information and just tabs through a new record/row or cursors down the app blows up. If they cursor up without entering any data, the blank field procedure for these protected fields engages fine.
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Aug 13, 2010
I am trying to populate a textbox.text with a value with a record from a datagrid. I can get my value from the datagrid by the following
Dim eRow As Integer
eRow = datagrid.CurrentRow.Index
txtSelecteditem.Text = datagrid.Item(0, eRow).Value
This all works fin when there is a value in the cell it is picking up. However, I hit a problem when this filed is blank.
The error I get is: Conversion from type 'DBNull' to type 'String' is not valid.
How can I get the textbox to populate with null if the field is null.
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May 17, 2009
I have datagrid, a textbox and a button .. the user puts a value in the textbox, and when he presses the button it should search through the datagrid for that value, if found, 1 of 2 things may happen:Or the datagrid only shows that value Or the value the user put in the textbox show indexed, like, with the blue thing over?
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Dec 12, 2010
I am trying to perform a search and this is as far as I got. I am trying to search through a datagrid for a match either by last name or ID. I know the ID search is almost working but not sure how to make it look for whats in the text box... how to match the value in the search text to the datagrid.
Private Sub SearchButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SearchButton.Click
Dim ind As String = 0
' Dim Result As String
Dim SearchArgument As String
[code]....
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Feb 15, 2012
i need bit of support in my vb coding. i've publish data onto a datagrid(in vb express 2010). i just want to highlight entire row once the search data is found(in lime color) and color should be remain in that particular row when searching next records. so that user would easily know which records are searched and which are not by looking @ the color.
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Jun 11, 2011
i want to search data according to textbox i want to write a code in eventstextbox1_keypress whenever you write a word L in textbox so the dgview row select the row where the row starts with L and after that i press I so the select dgview row whrer
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Apr 17, 2011
i am working on an assignment to search a value in datagridview column if value matched with input textbox then datagrid cursor should move to the cell having that searched vallue and if column has more than one searched values then cursor should move to next cell having that particular searched value and so on .e.g
----------
[code]....
suppose that if we search for value AROUT which is in cell nomber 3,5 and 7 when user hit the serch button first time then data grid cursor should move to the 3rd cell and when user again click search button then datagrid cursor should move to the 5th cell and when user click search button third time then datagrid cursor should move to the 7th cell i have tried many combination with FOR loop and IF condition but with following code i am able to search the string only once obviously if condition does not allow me to search a value more than once .the code is
for i as integer=1 to 90
If DataGridView1.CurrentCell.Value<>textbox1.text Then
DataGridView1.CurrentCell = DataGridView1.Item(0, i + 1)
End If
Next
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Mar 6, 2012
The problem is when I search through a textbox and nothing matches the search query, I accidentally click the column header which is the lastname then the error "Object reference not set to an instance of an object." pops up.
The highlighted part of my code is the text closed in quotation marks.
"If dgvStud.CurrentCell.Selected = Nothing Then"
btnEdit.Enabled = False
btnDelete.Enabled = False
Exit Sub
Else
btnEdit.Enabled = True
btnDelete.Enabled = True
End If
This code is under my dgv cell click event. Here is a screenshot for the column header where I found the error. [URL]
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Jan 17, 2011
I have put an Input box + Button in my main form to search items inside my DataGridView in Visual Basic 2008 Express Edition, i just dont know what codes to put in my button to enable searching items inside my DataGrid.
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Apr 6, 2009
I've tried a few different methods I could find in order to connect my VB .NET program to a book store's database. While I've been able to connect to it and display the contents of its tables in a DataGrid, I need to be able to search the tables and display specific records, depending on the contents of appropriate the adjacent text boxes.[code]This is a code I've used for a very similar process, just really aims to search a different field in the table. If this is easier to adapt into a code that allows searching and producing specific records in a database, please use this one.
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Jan 18, 2012
In my ASP.Net Web-Application, I'm getting this error: Conversion from type 'DBNull' to type 'Boolean' is not valid.
[Code]...
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Dec 13, 2011
I am teaching myself vb.net with visual studio 2010 and i have ran into a wall. I have a datagrid on my form that shows all of my customers that are in the dataset that was created in access 07. I have a search bar and check boxes to select which column name to search in. Whenever I search it throws up a strong typing exception,
System.Data.StrongTypingException was unhandled by user code
Message=The value for column 'PickupTime' in table 'CustomerRouteTable' is DBNull.
Source=EXBSTESTDatabase
[Code]....
I think this means that there is nothing in the field, but this is a field that nothing should be in. If i comment the throw exception out it moves on to the next one that has nothing in the field. I tried just putting 0's in all of them but it still gives the same exception.
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Nov 9, 2011
I am receiving this error on this line
ctl.Value = CType(Me.Value, DateTime)
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Jan 19, 2012
I have been having an error that DBNull cannot be returned as a String and after hunting around I came up with the folowing but have had no sucess. it is very inportant that this code can handle DBNull as it will encounter this often.
[Code]...
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Mar 10, 2010
Dim k as nullable(of double)I am INSERTING a rec in database containing K (sometimes it has some value otherwise a null) It works ok.But when i UPDATE a rec and assign a field the value of k and when k is NULL
it gives me an error that you cannot assign a NULL , you should use DBNULL.But i think DBNULL.value can only be assigned to an object not to double.
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Nov 12, 2009
I need to make something like :
if isdbnull(value) or value = something then
'do something
else
[code].....
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Sep 29, 2009
So I'm importing Excel data using ADO into a DataTable then pushing out to an Access DB. A couple of the Excel columns have several blank cells that I would like to change to a zero before pushing it out. How can I check/change the DT null values to zero? I've done some searching but was wondering if I could do it without a loop.
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Mar 8, 2010
Why does the following query raise the error below for a row with a NULL value for barrel when I explicitly filter out those rows in the Where clause?
Dim query = From row As dbDataSet.conformalRow In dbDataSet.Tables("conformal") _
Where Not IsDBNull(row.Cal) AndAlso tiCal_drop.Text = row.Cal _
AndAlso Not IsDBNull(row.Tran) AndAlso tiTrans_drop.Text = row.Tran _
[code]....
Run-time exception thrown : System.Data.StrongTypingException - The value for column 'barrel' in table 'conformal' is DBNull.
How should my query / condition be rewritten to work as I intended?
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Jan 13, 2012
Why does the following code: A = not IsDBNull(CurRow("BuyBook")) AndAlso CType(CurRow("BuyBook"), string) = "Yes" results in the following error:
Conversion from type 'DBNull' to type 'String' is not valid.
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Nov 17, 2010
I am writing a program that pulls data from a database.For each table that I pull data from, I write a series of If Than Else Statments to catch any null values and assign Nothing so as not to throw an exception.Is there a way to check against a DBNull value without writing an If THan Else Statment for each column I am pulling from the database?
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Feb 10, 2010
I have simple app code:
Dim sw As New StreamWriter(FileName, False, System.Text.Encoding.GetEncoding(Encoding))
Dim adapterPositions As New MyDatabase1DataSetTableAdapters.PositionsTableAdapter
[Code]....
How I can check column is DBNull or not?
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Apr 17, 2009
Is it possible to converty a type System.DBNULL to a string type?
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Jun 5, 2011
I wants to ask how to convert DBNull to Date type?
For Each row As DataRow In dt.Rows
i = 0
Dim array As Object = row.ItemArray
[Code]....
array(i + 10) is datetime type, in the program above, if the Datetime column contains items, it still can run. However, when it loops to a row where the Datetime column does not have value of datetime (or the column is null), then an error " Conversion from type 'DBNull' to type 'Date' is not valid" is occured. I tried to use the if statements as program above but it seems like cannot works.
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Nov 24, 2009
this code i pick from grauva khanna... it working..but for one coulmn only.. my question is ..how to manipulate every column with dbnull.value
'If TextBox1.Text.Trim = "" And TextBox2.Text.Trim = "" And TextBox3.Text.Trim = "" And TextBox4.Text.Trim = "" Then
'DT.Rows.Add(DBNull.Value, DBNull.Value, DBNull.Value, DBNull.Value)
[Code].....
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Jun 6, 2011
I have a piece of code im working on and is stuck on Select Sum statement which keeps returning a Conversion from type DBNull to type Decimal is invalid. Below is the code and Im working with a Access Database. Everything works good if the Batch Number exists and its when the Batch Number does not exist.
[Code]...
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Dec 14, 2009
I have a form with some textboxes in it. Not all the boxes are mandatory fields. I also have a store procedure that saves the records to the DB. when I try to save a record, I get an error PLS-00306. I am passing the required number of parameters to the sp. When I populate all the fields, the record is saved but NOT when some fields are left blank.
If txtInvoiceRef.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varInvoiceID", OracleDbType.Varchar2, 50, ParameterDirection.Input)).Value = System.DBNull.Value
ElseIf txtPaymentDate.Text = Nothing Then
strSQL.Parameters.Add(New OracleParameter("varPaymentDate", OracleDbType.Date,
[Code] .....
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Jun 30, 2010
I have a dgv with some checkbox columns. When I load data in the dgv, and I want to check in the cellcontent_click event, whether an another cell value (this is a checkbox cell too) is true or false, I get the error that the operator = is not defined for
dbnull value and for boolean. F.e.:
If
dgvegyenijogok.Rows(e.RowIndex).Cells(3).Value = True
And
dgvegyenijogok.Rows(e.RowIndex).Cells(4).Value = True
And[code]......
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May 20, 2010
I've got the following LINQ Statement:[code]invRecord.Pack_Num is a field of type Integer. This means that when I try to access it, if it is DBNull I get a StronglyTypedException. The above code throws this exception. If, however, I remove the "invRecord.Pack_Num = PSNum" and in its place put something like "True", the code works fine. So I guess my question is, why is that that invRecord.IsPack_NumNull() returns False when the value is in fact DBNull and what can I use as a conditional instead? I've been beating my head against the wall for a while now and I can't find a solution to this problem.
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Oct 12, 2011
how to set a field in a dataset table back to <DBNULL>?
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