I am building a vb.net application for a client, and there is a problem. I am connecting to a mySQL server, and using the UPDATE command to update certain fields to the specified values, however, once I run this code, the fields on the mySQL server turn EMPTY. Here is my code :
Sub updateresidents()
'MAKES NO SENSE; UPDATES EMPTY FIELDS ON mySQL SIDE??!!!!!!!!!!!!!!!!!!
Dim connection As MySqlConnection
[Code]....
why this code returns the property names as column headers and empty fields?
Dim table As New List(Of SalesPersonClass.SalesPersonClass)
Dim i As Integer
For i = 0 To salesPeople.GetUpperBound(0)
table.Add(salesPeople(i))
Next
dgSalesPeople.DataSource = table
I have been on a database project for a while now. I wanted to be able to make changes to my database using the update command of a Datagridview control.However, I have been faced with a series of unsuccessful outcomes.I want to do this how do I go about it?
[Code]...
I can't figure out how to update a field in a MySQL db using MySQL Connector Net 5.2.5. Can anyone show an example code?
View 2 RepliesPrivate Declare Function GetPrivateProfileString Lib "kernel32" Alias _
"GetPrivateProfileStringA" (ByVal lpApplicationName As String, _
ByVal lpKeyName As String, _
ByVal lpDefault As String, _
ByVal lpReturnedString As String, _
ByVal nSize As Integer, ByVal lpFileName As String) As Integer
Dim value As String = ""
Dim length As Integer
Dim IniFileName As String
GetPrivateProfileString("Config", "UserName", "None", value, length, IniFileName)
but value contains an empty string I confes to being a VB n00b, less than a week, in fact, but I can't see what's wrong there. The file exists, it contains a section called "Config" which has an entry called "UserName" with a value - but even if not, wouldn't value take the default?
Edit: It's not returning an empty string - it's returning whatever I initialize value to before calling GetPrivateProfileString().
Which is to say that if I Dim value As String = "xxx" then it stil contains "xxx" after the call and not the default value.
Private Declare Function GetPrivateProfileString Lib "kernel32" Alias _
"GetPrivateProfileStringA" (ByVal lpApplicationName As String, _
ByVal lpKeyName As String, _
[code].....
I need to allow hard returns and bullet points in all Text fields
View 1 RepliesWhy MS Access adodb in .NET returns 34 in fieldcount when table has 42 fields ?I see 42 fields in table of my MS Access mdb database. But ADODB layer in .NET sees only 34 fields. The Outofrange exception occures when I am calling method getOrdinal("FieldName") of reader class.
View 1 RepliesHow can I implement a sub routine or function that does a test for number validation in text fields and then also returns the value of the text fields (if they were valid) back to the main routine?
View 4 RepliesI have a query that 'selects' object of a type:
Dim l as IList(Of Foo) = (From dataRow As DataRow In table.Select()
Where CStr(dataRow("Column1")) = "A"
Select New Foo(CStr(dataRow("Column1")), _
CStr(dataRow("Column2")))).ToList()
What's happening is that if i set a break-point to the constructor of Foo and step, the constructor is hit and the parameters are loaded with the arguments. However, l has empty Foo objects (the members in every object are Nothing). What could be happening here?
treeView control which has been plaguing me for the last few days.
I'm not exactly sure what is causing this problem to arise, so I will just explain what my program is trying to do.
I am building an application which will have plugin support. I have created a Plugin interface, which is implemented by each plugin, as well as a host interface, which is implemented only by the host application.
Each plugin has an Action subroutine, and when finished, it is supposed to call the ExecutionComplete subroutine in the host interface.
Now, onto the problem. I have a treeView on the host form, which has several nodes in it. If I create a button on the form which displays a message box with treeView.nodes.count, it shows up fine, and everything works as expected. If I attempt to display the same messagebox from the ExecutionComplete subroutine, it also gives the correct number of nodes.
This is where things get a little weird. I have implemented a save feature into my program, so you can save and load data. For some weird reason, if you have loaded the data from a file, rather than adding each node manually, it now returns an empty node collection ONLY if I try to access it from ExecutionComplete. If I try to access the nodes from a button, it still returns the correct values!
What could it possibly be about the ExecutionComplete subroutine that makes it return a value any different than what is returned when the exact same code is placed in a button click event? And why does it only happen when I've loaded the data from a file? I just don't understand how loading it from a file is any different than them adding the nodes manually. The nodes are definitely being added, as I can see them, and the button click event can also see them. Also, ExecutionComplete is obviously able to read the contents of the treeView, because it works just fine if the user has set up the treeView manually.
i'm having a problem w/this conversion code. as the title describes, the first file converted returns w/empty content, but w/the file name.the rest of the files are ok. here is the code, just paste in form and run.. i meant, run the app. ;o)
Public Class Form1
Private btn As New Button With {.Location = New Point(0, 0), .Size = New Size(59, 23), .Text = "txt folder"}[code]...
i just need to convert the files and have them return complete.there is an invisible richtextbox, which i needed to show files being converted in a past project..now, i need to get rid of that richtextbox if possible. too much extra work for a user's p.c...i am not at all familiar with changing extensions, etc..
I get an empty string when calling the .Text property. Refer below for snippet:[code]The internet search advises to use Items(col).Cells(2).FindControl(..), the problem with that is FindControl finds the control by ID, BoundColumn doesn't allow you to insert an ID for it.
View 1 RepliesI used to run into problems with this in VB6, too...
If Not ds_Students.Tables(0).Rows(0).Item("ClassDay2").IsNullOrEmpty Then
txtClassDay2.Text = ds_Students.Tables(0).Rows(0).Item("ClassDay2")
End If
This produces "Public member 'IsNullOrEmpty' on type 'DBNull' not found."
And is there a different test for fields of different data types?
How to avoid getting empty fields in a databound combo box?
View 2 RepliesI'm trying to add a service company from a vb form to an SQL table. It works as long as I enter something in every field on the form. If not I get a syntax error so I thought I should check that the field values were not null
I've tried to add a sub to check for blanks but it's not working
btw the table will allow nulls for all fields
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Try
[Code].....
the sub I right now is this:
Code:
Private Sub DetermineTicketNumber()
Dim objConnection As SqlConnection = New SqlConnection(strConnectionString)
Dim objDataAdapter As New SqlDataAdapter
[code]....
My question is, how do I access the value that MAX() is returning from my SQL query?
I have a database with lots of fields, some of which are still empty and are to be filled in at a later stage. Is there any way of writing an IF statement (or any other method) that will allow these empty records to be 'shown' in my textboxes in Visual Studio, without receiving the error:
Conversion from type 'DBNull' to type 'String' is not valid.
How to tell the program that if the field is empty to skip it and go to the next step. I have tried IsEmpty (but it tells me the variable IsEmpty was not declared), I have tried to use different If statements but in most cases I get the message
"Conversion from type 'DBNull' to type 'String' is not valid."
I tried using an integer variable and setting it to
'Test = CStr(dt.Rows(I)("socSecNumber")).Length'.
It works for the first step (which makes sense b/c socSecNumber is never empty), but when I set the 2nd and 3rd ones
(TestFName = CStr(dt.Rows(I)("firstName")).Length TestLName = CStr(dt.Rows(I)("lastName")).Length If TestFName > 0 And TestLName > 0 Then...)
Then I am back to getting the message
'Conversion from type 'DBNull' to type 'String' is not valid'.
I do not know anything about recordset and when I did try to use it it displayed the message something like 'get and set are no longer allowed'.
The entire function is below:
Private Sub BtnCreateLetter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCreateLetter.Click
Dim SSN As String = TxtBxSSN.Text
Dim dt As New DataTable()
[Code] .....
Is it possible to include something in the SELECT from table? Such as:
"SELECT * FROM" & Students & "WHERE" * NOT DBNull
or
I do not know if it is possible to use variables in the SELECT from table code but if it is I thought perhaps could make a variable named FieldContents and pass it to a function that would do something like:
"SELECT * FROM" & Students & "WHERE" * FieldContents LIKE '[A-Z]'
The new command text returns data with schema different from the schema of the main query. Check your query's command text if this is not desired. I am getting this warning, whenever I add a query in a Strongly Typed DataSet which returns a single column.
Ex
SELECT DISTINCT Building
FROM Room
ORDER BY Building
When I give this query it will show me a warning. Because warning leads to a constraint error when ever i call the same function in a windows form.
Im having a problem passing a date and time stamp from vb to mysql. My code is as follows:ComboBox1.Text.ToUpper() & "', '" & TextBox1.Text & "', '" & Now() & "'"Where the comboBox populates the first field, the textbox populates the second and in the third I get 0000-00-00 00:00:00. I have formatted the field as date and time - which is what I am after
View 8 RepliesThe vb.net "WithEvents" syntax is very useful, but if a WithEvents field which references a long-lived object is not nulled out, it will often constitute a memory leak.Is there any easy way for a Dispose routine to have vb.net automatically clear out all WithEvents fields and unsubscribe them?
I've figured out a nice way to wrap the creation of disposable fields so that they will be automatically Disposed when the containing object is disposed, without having to individually list such objects. Is there any way to take care of WithEvents fields without having to manually null them out in the Dispose routine?
EDIT:Since there was no response indicating a built-in way to do it without reflection, is there any built-in means of using reflection to determine whether a particular property is a VB automatic implementation of a WithEvents "field"? I know that a WithEvents "field" called "foo" is implemented as a property called "foo" and a field called "_foo", but that's such a common naming pattern that I wouldn't count on it. Is there some attribute that could be used to determine which properties need to be auto-nulled?
I create table using sql developer
create table tablenodes
(
nodeNo int ,
nodeName varchar2(50),
centerX int ,
centerY int,
][Code]...
I have a problem in updating statements, can't write it correctly, every time I try to edit it, gives me different error (ora-01036 illegal variable name/number, missing expression, invalid identifier).
I have an issue with a data base updating it won't update for me in debgging mode it is stopping here on this bit of code which is highlighted in red. the error which comes up is .(update requires a valid update command when passed datarow collection with modified rows.)
Public Sub UpdateDataSource(ByVal ChangedRows As database.dataset1)
Try
'The data source only needs to be updated if there are changes pending.
If (Not (ChangedRows) Is Nothing) Then
[CODE]...
I am create a mysql table with TIME Data type fields. Like FROMTIME and TOTIME. And some insert data to that table. And that data is view through DataGridView. I can show all data in DATAGRIDVIEW. But, Have a error data, when current row click time ( Error data is : DataGridViewTextCell {ColumnIndex=0,RowIndex=0}.
How to store TIME types to Variables or Control;
I'm strugling the whole day with the next JSON string
{
"0":{"link":"afbeeldingenplaatje1.jpg"},
"1":{"link":"afbeeldingenplaatje2.jpg"},
"2":{"link":"afbeeldingenplaatje3.jpg"}
}
How can i deserialize this? What's wrong with the next code (vb.net)
Public Class DataString
Private m_link As String
Public Property link() As String
Get
[CODE]...
It returns always an empty result.
Here's my code
Dim suppQuery As String = "SELECT [Supplier ID],[Company],[Last Name],[First Name],[Email Address],[Mobile Phone],[Office Phone],[Address],[City],[ZIP/Postal Code],[Notes] FROM [Suppliers]"
Dim dsSupp As New DataSet
Dim daSupp As New OleDbDataAdapter(suppQuery, cnPharma)
[CODE]...
It errors on the da.Update line and by the way if it helps, the text fields are a product of datarowview. that is when you select an item on the listbox the details of that appears on the text fields. and my goal is i could edit those text fields and save them.
We know:"UPDATE tt SET Points=" & iPoints & " WHERE Ref='" & sRef & "'"Can we update several records using UPDATE command at one time?
View 4 RepliesI have a program that auto fills a section on a webpage, how can i tell this command to ignore the textbox if its empty? If i dont the software crashes because the following command needs the box filled in order to proceed.
[Code]...
I'm trying to update an Access database by using an OLE connection, retrieving the information from textboxes where the user enters the new information.All the fields in my Access table are required fields, so I have validated that some info is entered in each one of the textboxes and that is the correct data type.But when I run the update query I get an error message saying something like values haven't been entered for some required parameters (my Visual Studio is the Spanish version, so I can't give the exact error message in English).The bit of code where the error occurs is inside the procedure called by my "Ok" button:
Dim campo1, campo2, campo3, campo4, campo5 As String
Dim campo6, campo7, campo8 As Double
Dim campo9, campo10 As Integer
[code]....
(I didn't post the whole code inside the procedure, but of course I'm creating the connection and everything)
The table has 10 fields, and the data is read from the textboxes and stored in variables (campo1, campo2, campo3, etc.), which I'm then using in the "set" query command.
"id" is the first field from the selected row in the datagrid, which I'm sending as a parameter to the procedure called by the "OK" button.The error message shows at runtime, so I'm guessing it's something in the query. Am I writing it correctly?