Count Child Record And Show Zero If Empty
Jul 4, 2011
I'm fine with both C# and VB.NET..I have two tables. Authors and Books. It's a one to many relationship, Authors to Books. I'm writing a query to show how many books that each author has.[code]But in the Authors table, there are some authors without any books yet. For example, there two authors, Author D and Author E that have no books yet. I want to write query that includes all authors and number of ther books, even though they don't have any book yet, no record in the Books table yet.
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Feb 21, 2010
While I've previously many years of relational databases and procedural languages, I'm stumbling with Visual Basic. In this problem, the simple situation is that I have two files, parent and child. The primary key of the parent file (Area file) is linked by a relation to one of the two fields that makes up the primary key in the child file (Project file) (unique key is formed from 'area' and 'project'). I have the default table adapters created on both files. I have created two maintenance forms showing one each of the two files in datagrid view format.I can create some records in the Parent (Area) file, but when I try to create a record in the child (Project) file, using one of the valid key values from the Area file, I get the 'ForeignKeyConstraint [relation name] requires the child key values [actual value] to exist in the parent table' which I'm absolutely definitely sure it does.
I haven't done any actual coding for those two maintenance forms, just dragged-and-dropped the files from the data sources screen onto separate forms so it creates the controls itself. But I can't work out, if it already knows the data does exist because I can load it back in to the Area maintence form, why it can't check itself to find out the record does exist. Why does it think the record from the parent record doesn't exist? It does exactly the same thing, whether or not the database is in access or SQL Server Express. I have all the latest updates.
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May 27, 2011
Visual Studio Pro 2010 Win 7 64 bit running bootstrapped to a MacBook Pro i5 (blasphemer!!!) works really well though!!New to vb.net, have used vb6 for several years and finding the transition interesting to say the least.I have an access database with a vb.net front end all auto bound by the connection and binding wizards (I know, I know...) Not too complicated, but a simple 2 table related db. On the form the parent table shows customer details with the child table related and displayed by datagrid. I have a field in the child table for images and I have figured out how to store and retrieve images to the db. I am using the datagrid.rowheadermouseclick event to reload the picturebox on the main form as I click down the child table datagrid. Now I need to be able to click the bindingnavigator, go to the next record and have the program reload the image for the next child record. The problem is I'm trying to use an event from either the datagrid or bindingnavigator to reload the picturebox in the child table after moving to the next record, but all of the events I am trying are firing before the next record is moved to and therefor the logic I'm using to retrieve the image from the db is not working.
Anyone with an idea on how to move to the next record and then run my logic to populate the picturebox? What events might I use that fire after the next record has been populated? I know this is probably not that hard, but I have been racking my brain all day now.
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Apr 8, 2010
MsgBox(MyDataSet.mytable.Rows.Count)
Gives 0, why?
The table has data!
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Sep 25, 2008
I have a problem with bound controls and a bindingsource. I'm using vb 2008 and .net 2.0.I have a few text boxes bound to columns in the binding source.The backend is a Access database.
I'm using a bindingnavigator to add a new record.The additem event works fine.If the user clicks an icon to cancel edit, the code executes bindingsource.canceledit. This seems to work fine. The row count on the navigator returns to the correct number before the addnew event occurred. However, the bindingsource seems to have an empty record in it. As the bindingsource navigates, it eventually gets to the empty record depending on where it's position was when the addnew event fired.
The error received is an invalidcastexception. This error occurs because the record is repostionedand each time this occurs the code performs calculations using values from the bound controls.But when it navigates to the empty record, the values in the bound controls are null.Is there other code besides canceledit to remove the empty record?
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Jun 16, 2011
I'm trying to retrieve some data from an Excel with the following [code]...
At some point the Recordset encounters an empty cell which it can't assign as a to Recordset.Fields("BG").Value. VB2010 will then throw an error: When casting from a number, the value must be a number less than infinity.
correct syntax for checking on an empty cell?
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Jan 31, 2012
I have this database table called people[code]...
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Jun 14, 2008
I know how to display or manipulate (add,delete,update,search) records using the OleDbDataReader and OleDbCommand class. But I'm clueless in getting the total record on a query.
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Jan 28, 2011
I am trying to figure out how to get the max record count before i populate a listview grid. I'm using the Oracle 10g DB and I've tried:
SELECT COUNT(*) as countNum, status, date, theTitle, theMessage, date2 " & _
"FROM blah blah...
messagebox.show(dr(0))
But that makes the SQL query crash. It doesnt seem as though i am about to put anything related to "count" in my query or it will crash so is there any other way i can see how many records it returns other than that?
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Jun 6, 2012
I've written some code to try some thing. I don't get an error message. However, the record count return " zero". I declare some objects and make a connection. That all works fine. But no records.
Here's the code :
Public Class Form1
Dim vtest As VariantType
Dim cn As ADODB.Connection
Dim rs As ADODB.Recordset
Dim cmd As ADODB.Command
[Code] .....
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Mar 23, 2009
what is the maximum record count for a datagrid in vb.net?
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Jan 28, 2011
I am trying to fetch my record count in my following query:
myCommand = New OleDbCommand("SELECT status, date, theTitle,
theMessage, date2, COUNT(*) over () as countNum
FROM Blah blah...[code].....
But it just closes my program. If i comment that out then it populates just fine and doesn't close.What could i do to correct this?
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Nov 9, 2011
I'm very new to linq and I'm trying to come up with a linq query against a dataset that will return a max count value based on grouping records.[code]...
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Jun 10, 2010
I currently have the below code to list all tables in a MS Access Database, what I would like to do is alos COUNT the TOTAL records within each table and display that info in a listview control.
how to get that info.
This is the code I am currently using to get the list of tables from the database:
Dim userTables As DataTable = Nothing
Dim i As Integer
Dim restrictions() As String = New String(3) {}
[Code]....
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Jan 29, 2012
How to i display how many records that i have in a label on my main form for example if i had 3 table called Cusotmers, Orders, Products
How do i get it to show the total amount of each table on label 1 label 2 label 3?
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Apr 2, 2012
I've got a grid view. I want it to say "you have nothing to show" if there are no details.
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
If GridView1.Rows.Count = 0 Then
[Code].....
However; it seems to be working backwards and showing the message when there is data to display in the gird view and continues to be a blank page when there is not data to display in the grid view.
I've tried a variety of combinations with the below IF statement below but no success.
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Mar 7, 2010
I have a form reading from an Access file now everything seems fine until i go to add record if i then press the first Btn or pre Btn without entering any data then it gives me the error Column 'Membership ID' does not allow nulls. [code] i have been trying to get it to show a msgbox saying the box cannot be left empty but so far no luck.
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May 20, 2010
I have the following code and I want to say that if the datagridview - dgvImportData is empty then say this message otherwise say the other message.
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May 17, 2009
is there a way to show in datagrid only those row that has column that is empty, im using this code
Me.DataGridView1.DataSource = ds.Tables("0").Copy() but it shows all the data from my table.
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Jun 18, 2011
my table name is "temp", and one of the field is item_id..how can i count how much item_id was added in this table...??is the code "SELECT item_id, COUNT(*) FROM temp GROUP BY item_id"it doesn't work.. i'm using OLEDB connection and can't use sql property
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Jul 26, 2010
As you all know, If the dataBase requires a numerical value then an error will occur when the user tries to insert the incorrect data type. With the code below after the user types in a value beside an int value type then it will go into an Loop through more than what is needed. How can I apply the same logic but allow the program not to check the 60 rows (I set the row size to 60). I want to break out of it if there are blanks ONLY if a row is blank and not for a black cell, because if the user leaves one cell blank then it would loop through the 'for each' for how many rows that they is. Initially there are 60 rows.
MIS
For Each item As DataGridViewRow In dgvLaser.Rows
If IsNumeric(item.Cells(3)) Then
Exit For
Else
MessageBox.Show("Check Record Count. Numerical values only..!")
End If
Next
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Jul 13, 2011
Working on an VB/ASP website in Visual Studio 2008. Getting the error "You cannot add or change a record because a related record is required in table 'abc'
It is true that table xyz (the target of the INSERT) is in a parent-child relationship with table abc. The PK in abc is a column RequestID_lng. The FK column in xyz is also named RequestID_lng
This is the only relationship these 2 tables are in.
I am trying to add a row in xyz with a value of 45 in the FK. There is already, previous to this action, a row in table abc with a value of 45 in the PK. So the parent already exists for this child.
I have used the watch window to copy my SQL code for the INSERT query that is being executed. I pasted that code into a new query in the Access DB and executed it without problem - it actually added the row that .Net should have.[code]...
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Sep 3, 2009
DataRelation is used to create parent child relation ship between ParentTable and ChildTable Its working fine. ChildTable is displayed in a datagridview. But now how to get selected record from child table?
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Jan 31, 2009
i post a new thread with same in my previous topic Using If Statement. If my textbox is empty or no value then clicking a button will show a message box..and if trying to put a value will do event.inserting a record. all i need to know how can i make it that thing.if i try to load without any if statement and trying load it btnok will load a insert record. Just like a LogIn form that will pressing a ok button with no value will display a message box Invalid Username
[Code]...
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Apr 4, 2011
I have the following form and I'm trying to add a error to the page that if the recordset = 0 then there is a message on the web page stating that there were no results. What's the best way to do that?
Imports System.Data.SqlClient
Imports System.Data
Partial Class _Default
[code].....
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Jul 7, 2009
We are bysy with making a crystal report in vs2005 / 2008
We want to print the address of a bussiness, see picture-1.jpg
If field-2 of the second record isnt filled in we get the the result see picture-2.jpg
In the crystal report we don't want to show the empty information of field-2, see picture-3.jpg Is it possible to create this in a crystal report?
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Apr 14, 2011
records with filter property gives the correct recordcount but it displays few records when bind to the mshflexgrid
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May 17, 2012
There are 3 textboxes->textbox1,textbox2,textbox3 and 1 button.In textbox1 bname will be stored and in textbox2 aname is stored.Bname and aname are columns of databasetable.This are not unique.There are same bnames and anames records.What I am trying to do is:when the user clicks on button then the code should match textbox1 and textbox2 with the databasetable and get the count of rows that match this data.
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Aug 19, 2010
i have made a button that opens a msgbox dialog what i need is to make it show a msgbox with an empty textbox inside and an ok cancel button,so when a user clicks it,it appears and asks for an url string and then,if uses pressed ok,the url should be placed as a movie to axshochwaveflashobject like this Private Sub FromUrlToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles FromUrlToolStripMenuItem.Click If FromUrlToolStripMenuItem.Pressed Then MsgBox("emptytextbox",title "Enter the url") If MsgBoxResult = ok Then AxShockwaveFlash1.Movie = "msgbox answer"AxShockwaveFlash1.Refresh() End Sub
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Jun 21, 2010
I have so many form to manage. I want to count the instances of a particular form. For example, if I show my form1 two times then there must be a counter for my form1 and if I also shown my form2 another counter for form2.I want to do this to minimize the instances of forms to be shown so that my resources will not burden to much.I want my code to be generic so that I can easily call it for my other forms.
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