I'm using VS2010 and SQLServer 2008. I'm trying to test for DBNull in datafields, but every formulation of a test I have imagined (or found) throws an error. Specifically,"The value for column 'ColumnName' in table 'TableName' is DBNull." (system.data.strongTypingException).Well, not too helpful. I know it's DBNull, and I want VB to recognize this.Here is what I've tried so far (all with the same result).
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I am building a data based application using VB 2008 an SQL Express. I need to create textboxes on my form using code, (With & End With) method. I need a simple code string that will allow the app to check if the field to wich the textbox wil be databound is Nul, If so the textbox will not be created.
View 8 RepliesI am currently creating an application to track timekeeping (a clock in/out system) and I am trying to work out the best way to do this.
I have a Main Form which contains buttons to ;
- Log in
- Out for Break
- In from Break
- Log out
When a user presses the "log in" button the logon form appears, the user then enters their username and password. What happens next is where I would like the help.
Process is as follows:Click Logon Enter Username/Password Check Logon Form for errors (eg no password etc) Check User is in Database (using SQL query) If user is in DB and username and pass are ok then refer back to the main form to perform Stored Procedure for what the user wants to do (eg logon or or out for break etc). Set label on main form to show user as logged on My question is should I be using a public variable and calling the main form again or in the user logon form having 4 options and using an IF ELSE to select the appropriate Stored Procedure?
I am pulling data from a local MSSQL database using a stored procedure, then send the data to a web service. Every part of the component works well except for a pesky problem will a DBNull being returned from the DataRow field, when I know that the field is not null and has valid data. The database and associated INSERT statements that add to this field are designed to not allow NULL entries. When I debug break the program on or right before the line that throws the error I see that the field has valid data for the current row.If I add a null check to the code (as below) the operation continues as normal:
Dim dataResultsTable = Me.myViewTableAdapter.GetData(int)
For Each myDataRow In dataResultsTable.Rows
If worker.CancellationPending Then
[code]....
Why is the read operation returning DBNull instead of the data in the database?
EDIT: Just to be clear, the operation does return the proper data, but the data is not being saved into the variable.
im trying to save data (0 or 1) from vb2010 to SQL2008.
How can I do it inside vb2010? In class or form? which 1 is recommended?
The following is I write in form class:
If Trim(CChar(cElectrical)) = CheckState.Checked Then
loDataAdpr.InsertCommand.Parameters.Add("@scopee", OleDbType.Char).Value = "1"
Else
loDataAdpr.InsertCommand.Parameters.Add("@scopee", OleDbType.Char).Value = "0"
End If
how to set a field in a dataset table back to <DBNULL>?
View 4 RepliesLets say I have a form with several Textboxes that are all bound to "bindingsource1". I'd like to be able to check the field data type each textbox is bound to. Something like this,
Dim ctl As Control
For Each ctl In frm.Controls
If ctl.GetType.IsAssignableFrom(GetType(TextBox)) Then
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How to check if string entered in a text box matches a field in a data table
I have a form with two text boxes for users to enter their Username and Password. When they enter their details and click the 'Login' button I want their details to be
checked against data in a data table to see if they match or not. I am using an 'if...else' statement but can't work out the syntax to use. My code is as follows[code]...Check when string entered in a text box matches field in data table?
How to check if string entered in a text box matches a field in a data table.I have a form with two text boxes for users to enter their Username and Password. When they enter their details and click the 'Login' button I want their details to be checked against data in a data table to see if they match or not. I am using an 'if...else' statement but can't work out the syntax to use. My code is as follows:[code]The fields I want to match the textbox strings against in my database table are called 'Username' and 'Password'.
View 2 RepliesWhy 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.
I have simple app code:
Dim sw As New StreamWriter(FileName, False, System.Text.Encoding.GetEncoding(Encoding))
Dim adapterPositions As New MyDatabase1DataSetTableAdapters.PositionsTableAdapter
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How I can check column is DBNull or not?
This is my problem.I have a field set up in MS Access to Boolean YES/NO, this field is populated when the user check a checkbox on a windows form. If the user check a checkbox, the value is written as checked in the data field (MS Access).The problem is when I search for the user information, I need the information from the Data base to populate(return) to the windows form. Example: If I enter a users phone number and the user data is present, the form gets populated with the information the user previously entered which was store in the database.Example: If the user selected checkbox1 and submits the form. When I search for the user info, the check box should check(populate) because the user had checked it on submit.Here is what I have done:
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I am getting the check value correctly in the database using a Boolean.Here is one of the errors I am getting. Unable to cast object of type
'System.Boolean' to type 'System.Windows.Forms.CheckBox.I am having trouble putting the codes in a code tag or block
I have a Boolean that writes to a data field. The data field(column) is set to YES/NO, if the user check a checkbox, the value is written as check in the data field.The problem is when I search for the user information, I need to get to form to the state it was in when the user submitted it.
Example: If the use select checkbox1 and submits the form. When I search the form, I need to make that particular check box check.
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I am recieving this error on this line
ctl.Value = CType(Me.Value, DateTime)
Conversion from type 'DBNull' to type 'Date' is not valid.
I am using Data Grid View and This is a calendar Type Column
I'm trying to handle DBNull exception while reading data from database. It's my code:
...
Dim SQLRDAs SqlDataReader
...
val1= GetStringFromDB(Trim(SQLRD("Name")))
val2= GetStringFromDB(Trim(SQLRD("Level")))
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But still I get Conversion from type 'DBNull' to type 'String' is not valid. error.
I have a VB6 application that is accessing an sql server 2008 database using odbc. The application also accesses an ACCESS database. How can I create a temporary table in my ACCESS database using a table from the SQL database. I have tried the following:
SELECT GLTransaction.* INTO TempAPEntry0 In C:DOCUME~1DONNPS~1.000LOCALS~1TempCSAReport2564.MDB FROM GLTransaction WHERE GLTRSource = 641;
I have a problem writing dates from VB2010 into SQL2008.
I am forming DateofBirth from Comboboxes using DateSerial, so far so good.
DateOfBirth=DateSerial(DobYear, DobMonth, DobDay)
MsgBox(DateofBirth) displays the date as DD/MM/YYYY, as I would expect in the UK.
But, SQL is expecting the date in MM/DD/YYYY format. When the DD is below 12 the variable writes in the database, albeit with DD and MM the wrong way round. As soon as DD goes above 12, the program halts with an SQLException, obviously because SQL knows that MM can't be higher than 12.
I am going round in circles trying to work out the method to ensure that the date variable in the SQL INSERT statement is in the right format.
Basically I just want to set up exceptions for my program to prevent errors. The problem I am having is that sometimes the field name does not exist. For example, I am setting focus to the username text field named simply "username". However, if the entry does not exist (name=username) then I get an error. So what I need is a simple if statement to determine if it exist beforehand.
If Webbrowser1.Document.All("username").Exist Then
WebBrowser1.Document.All("username").Focus()
else
Messagebox.show("Field was not found!")
End If
I would like to pull a set of records in a SQL sproc by passing in a list of system.guid and also by passing in a list of integer keys.I can put the guids ihto a string, of course, but the question is - how do I quote the test values so they are recognized as UIDs by SQLIn essence I was to DECLARE @pklist AS VARCHAR(1000)-- This would look like "'45F4AE2A-D27C-D711-83FD-0008C7FA9683','EC824D02-D37C-D711-83FD-0008C7FA9683','BA8E4D02-D37C-D711-83FD-0008C7FA9683'" coming out of the execsql from vb .net - I think :-) but it seems it needs to look likeSET @pklist = '45F4AE2A-D27C-D711-83FD-0008C7FA9683,EC824D02-D37C-D711-83FD-0008C7FA9683,BA8E4D02-D37C-D711-83FD-0008C7FA9683'SELECT * from dbo.members WHERE members.cpk IN (@pklist)This only returns the record matching the first UID in the string. Is there something I can wrap a t-sql VARCHAR string with so each guid will be seen distinctly?In trying to do this with a list of integer keys, the problem is the value is seen as part of a string and is not cast to an integerIt would seem creating a table from a parsed version of the string passed in and then doing a JOIN would accomplish what I need as well, but struggling with the T-SQL syntax for that.
View 1 RepliesIs it possible to check a MS Access database table with existing entries to see if one of the fields is empty.[code]....
View 4 RepliesI have a problem with the Validation of a Integer-Field in my application.Its an Access DB on a Windows Form.I implemented the validation in DataSet.vb using an ErrorProvider on my Form.The field name is FNr and should not accept duplicate numbers.If the field value is changed, a query checks if the number already exists in the Datatable and if so it sets the error on that field.If the user tries to change the field to a number which is a duplicate I want to cancel the input back to the original number. This works but the
Error message is still shown by the ErrorProvider.The code is partially in DataSet.vb and in Form.vb
Public Class Funktionen
Private Sub FunktionenBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FunktionenBindingNavigatorSaveItem.Click
Me.Validate()[code]......
I'm looking for a walkthrough to help me design/develope a simple Blog that has the following parameters:Logon Screen Authentication Membership --> Email Lost Password.Simple Treeview like structure Topic-> Multiple Posts (2) levels deep only Historic calendar in right banner or someplace.Search Feature By (Topic, Username, Entry Date...etc)Does anybody know where I can find guidance otherwise left to my own devices this could take me a while, be nice to have at least a solid starting point in the correct direction.
View 2 RepliesI have an array set up to receive the names of forms when they open. The form name is sent as a Form not a String therefore when I run my code I cannot check for whether the field is empty in the normal way (ie. array(1) = "") as the "" are only usable with strings!
Dim Forms(24) As Form
Dim i As Integer
Dim Free As Integer = -1
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I only need a solution to do the same as array(1)="" but for windows forms.
How could you, update the fields on database if its data type is Y/N, and the method of updating is a checkbox??
View 1 RepliesMy application is like this : i have to search my data from database with some check box and text box when user select check box specific function go on and then when user enters some range of value in textbox then the result will shown in data grid view after that i can print it by selecting data
my vb.net code is as follow:
Imports System.Data
Imports System.Data.SqlClient
Public Class XtraForm1
[CODE]............
I m also pasting the demo picture.
In my ASP.Net Web-Application, I'm getting this error: Conversion from type 'DBNull' to type 'Boolean' is not valid.
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I want to UPDATE 1 field in a row of data but I want to select that row based upon 2 other changeable fields. I can not get the changeable fields to work. When I put in a integer in place of the @field, it works but when I use any @field name of field name, it does not work. HELP HELP
This works::
cmd.CommandText =
"UPDATE [dbo].[Healing] SET [Printed] = 'NO' WHERE (([Row] = 1) AND ([Flag] = 1))"
ReturnA = cmd.ExecuteNonQuery()
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I have a program for school project that has input fields for Name, Address, City, State and Zip. I need to error check so that the fields are not empty.I have used If statements that check to see if the fields are empty and shows a message box if they are but if I leave the whole form empty and click the button that activates it, all the if statements go- one by one instead of pausing for the user to input the required data.How do I check for data and make the program stay there until the data is input? I have tried TRY/CATCH but it won't catch this type of error.
this is the
'This program computes customer's bills at the pizza shop for all combinations of
'crusts, toppings, sizes and discounts
Option Strict On
Public Class PizzaForm
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I am creating a database in VB.NET for a movie rental place. I currently have three forms;
Member Information
DVD Information
Borrow DVDs
What I would like to do is when I am viewing a member's details, if I click a button 'Borrow DVD for Member', the member's ID number transfers over to the Borrow DVDs table in the Member ID which also would hold some information from the DVD Information table, but I'm sure if i can figure out how to do this firstly, I will be able to apply the same rule and work it out myself.I have been trying to use a query statement like;
INSERT INTO [Borrow DVDs].[Member ID] [IN goodstuffvideos.mdb]
SELECT [Member Information].[Member ID]
FROM [Member Information]
but that has been coming up with error codes and completely not working.
Borrow DVDs table fields are: Borrow ID, Member ID, DVD ID Number, Hiring Fee, Borrowing Limit?
DVD Information table fields are: DVD ID Number, Title, Rating, Hiring Fee, Borrowing Limit Member?
Information table fields are: Member ID, Family Name, Given Name, Address, Town/Suburb, Postcode?
The error coming up is; Error in INSERT statement. Unable to parse query text.And under that it says The query cannot be represented graphically in the Diagram and Criteria Pane.
How can I call my TextBox ID = "txtFromAddress" data to a table that I am trying to send? Right now it is just showing the text '& txtFromAddress' on the table on the email that I send.
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