I need to display data from many tables using a datagridview and I was wondering if this can be done using the JoinView class.I have used it before, but with one child table only. Now I have more child tables and I was wondering which approach (if many) would be the best.
The Dataset I am working with contains 28 relational DataTables but I only need 10 or so for the query, and they are structured like this[code]...
Dim obj_DataTable As New System.Data.DataTable("Category")
Dim obj_DataSet As New DataSet()
'Declaring the array of DataColum to hold the Primary Key Columns
[code].....
I have a dataset with 3 tables in it. Header, Detail and Customer.My form contains a Binding Navigator and I can click the "New" button, fill in the data and then when I press "Save" the data is written to my 3 tables BUT, the foreign key fields in the child tables contain NULL Values. The primary field in the Parent Table retains the correct data. So when I try to go back into the database the Parent record is displayed but no Child data because those records couldn't be linked in.
Once I am back in viewing the Parent record and then input data in those fields belonging to the child tables and press "SAVE" then the new records are saved just fine. It only seems to be when trying to create a new Parent record with Child records.
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This is another one of my "I think it's not possible but I need confirmation" questions.I have a base class for a bunch of child classes. Right now, this base class has a few common properties the children use, like Name. The base is an abstract class (MustInherit)Technically, this means that everytime a child class is instantiated, it lugs around, in memory, its own copy of Name. The thing is, Name is going to be a fixed value for all instances of a given child. I.e., Child1.Name will return "child_object1", and Child2.Name will return "child_object2".
View 1 RepliesI have Class1 and class2 which is inside class1, VB.NET code:
Public Class class1
Public varisbleX As Integer = 1
Public Class class2
[code]....
I have a 'property management class' that contains several functions and properties. I have several other classes that use the 'management class' as a property to derive the value of several of its other properties.Is there a way for me to reference the outer class from the 'management class' functions without having to pass it as a parameter? I ask because several different classes can have this 'management class' as a property and am having a hard time typing the parameter.
View 7 RepliesI'm having a nightmare with LINQ. I've got a table of Projects, and each project has many InvoiceHeaders. The Invoice header had a field AmountNet - the value of the invoice.
I want to retrive, for arguments sake, all of the fields from Projects, with the count of invoice headers and the sum of AmountNet. I.e. list of my projects, how many invoices I've raised and the value.
Doesn't sound hard does it.... well, I've just spent the best part of two hours charging through Google and SO to find a solution.
[Code]...
(VS2005 Professional)
My database's layout is as follows:
Identification (Parent table)
ID# (Primary Key, auto increase)
First Name
[Code]....
I am placing this three tables in three tabs by a tabcontrol. If I put two child tables in dataGridView in their tab, the insert(new record)/update to the tables works very well. When I put the child tables in details View, I can't get a new record updated. The problem with details view is that there is no AddressID and VehiclesID generated. In dataGridView, these IDs are automatically generated whenever a mouse enters into a cell in a row.
I am getting a System.Data.InvalidConstraintException" ForeignKeyConstraint CompanyPasswords requires the child key values(-1) to exist in the parent Table. When saving updates to the parent and child tables.My parent table consists of 3 columnsCompanyID (auto increment, pk)Company NameURLMy Child table consists of 4 columns PasswordID (auto increment, pk)CompanyID (fk)User NamePasswordHere is all the code on the form
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I have created a class for a Sports Facility. A facility has a Name, Status, Notes, etc as members of the class. This works well, I can create a new instance of an exisitng Sports Facility from the database, create a new instance, etc. All working well.What I am stuck on is accessing a list of Sports Facilities. I know I can create a new list by doing
Dim List As New List(Of Facility)
For Each fRow As DataRow In ds.Tables("Facilities").Rows
List.Add(New Facility(fRow.Item("FacilityID"))
Next
I have a Parent Class Called Fuselage that containsfour child classes called Forebody, CenterBody, AftBody, and CrossSection. CrossSection classcontains objects common to Forebody, CenterBody, and Aftbody (example: width). How do I access thewidth property in CrossSection from within the classForebody?
Public Class Fuselage
Dim Forebody As ClsSection
Dim Centerbody As ClsSection
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I am very new to vb. I have to create a registration form based on the a complainant form and offender form. Complainant form fills out, take the complainant_ID and parse it to registration form to load. Now when the registration form loads, it has registration_Id and complainant_ID, fills out necessary info and add an offender from the offender form and pass back the offender_ID to the registration form..now on this registration form, we have registration_ID, complainant_ID, and offender_ID..complainant and offender can have more than one registration..
Table structures:
Complainant table(complaint_ID, last, first)
Offender table(offender_ID, last, first)
Registration table(registration_ID, complainant_ID, offender_ID, type, desc)
What I have done so far:
Using separate dataset for each form. Complainant/Offender/Registration form load and save fine. But I do not know how to bind these Ids together so they stay in sync.. What I mean, when I add new complainant, take the complainant_Id, parse it to registration to create a new registration for that particular complainant, and also add an offender to that newly created registration, and pass offender_ID back to registration form. I am using visual studio 5 and sql express..
I have a problem that is frustrating me to no end, I have a overrideable function in a parent class, and the override function in the child class, like below:
[Code]...
When i debug, the value is produced, but it doesn't carry over to the parent class of ski.RetailPrice()what seems to be the problem here?
I am using ADO.NET Datasets in my VB Applications. I have a typed dataset with one Parent table and many child tables. I want to generate Identity Key when I insert data into Parent Table and then update the data in all child tables with the Same key (As Foregin key).At last, I want to update the dataset in Database(SQL Server08).Well, the above thing can be possible by first inserting Parent Table in Database directly, get the Identity column and than use to for Child tables.
View 4 RepliesI have two tables Employees and CafeLogs. Some employees can be cashiers and also customers at the Cafe shop.
Table structures:
Employees: EmployeeId(PK) , FirstName, LastName
CafeLogs: LogId (PK), CashierId, EmployeeId, Value, => CashierId and EmployeeId are the data from column EmployeeId of Empoyee table
Table relationship:
Employees 1:N CafeLogs (CashierId (FK))
[code]....
Right now I know how to select only LogId, Employee's name, and , Value, not with Cashier name yet.
Dim query = From log In db.CafeLogs _
Join emp In db.Employees On emp.EmployeeId Equals log.EmployeeId _
Select log.LogId, emp.FirsName, emp.LastName, log.Value
I have to convert a set of C# classes (class library) to SQL tables to be used by SQL Server, so that the data can be stored in a database and manipulated through the database.The problem is that the number of these classes is big (more than 1000 classes),and it would take a long time to setup manually such a database schema (tables,ndexes, stored procedures, etc.) - not to mention the class hierarchies that I need to maintain.
View 6 RepliesI'm writing an assignment in VB for a class which displays records from an Access database. It goes as follows:
From a "Rooms" table, I get the rooms to be displayed in a combo box along with 3 checkboxes which will tell me if they have a jacuzzi, private access of a fire place. From a different table in the same database I need to display in text boxes the bed size, weekday and weekend prices for booking each room. The text boxes should display the correct information according to what was selected in the combo box, but I can't get that to work! The checkboxes work fine, but the text boxes stay the same.
Here's what I have so far:
Private Sub Rooms_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Try
Dim RoomsData As New RoomsDataTier
Dim RoomsDataSet As New CottagesDataSet
RoomsDataSet = RoomsData.GetRooms
[Code] .....
I need some expert help in achieving this task. I have an xml file which will be emailed to me everyday. I need to loop through the xml and create tables in a database based on the xml nodes and their attributes. looking at the following xml fragment for example: Code:
So based on the above xml, I would have to create a Shipment table as a Parent with fields like ShipmentIdentifier. Then I would have to create an Event table with the ShipmentID as a foreign key and fields like Source, Code. Basically a field for each node. Then if there are columns in the table that are new, I would have to modify the table and add the column. I only have to create tables where there are child nodes or where the nodes have attributes.
Im working with MDI parent/child objects. when closing the child objects i need the child to check to see if it is the last child object before closing. i couldn't find anything on google, maybe im searching for the wrong thing.
View 2 RepliesI have a base class which needs to define an enumeration:
BaseClass
- SomeEnum
I then need to create two derived classes from the base class and extend the values in the enumeration:
ChildClass1 : BaseClass
- SomeEnum
- SomeEnumValue1
[code]....
In C# or VB.NET can someone provide the syntax to do this?
I would like to have a form class that is called from a button on a parent form and would like a button on the child form to set a property on the parent form. Can anyone explain the best way to go about this or direct me to a good article?
[Code]...
How do I force the Visual Studio compiler to generate an error when a required method is not being called in the constructor of a child class? Like when you edit the form designer code, the compiler complains when InitializeComponent()isn't the first call in the constructor of a form. Is this even possible in VB.NET?
View 2 RepliesVB Reference parent member of a class through a child when using List Of(T)?
View 1 RepliesI have three tables: BOOKS(BookID, Title, Author) CLASSES(ClassID, Title, MajorID,BookID) and MAJORS(MajorID, Description). I added these three tables to a LINQ to SQL class (UBooks.dbml) and then connected to the data sources. Then declared DataContext.
Using LINQ, my goal is to display all books in a grid which I have done with:
Dim allBooks = From Books In db.Books _
Order By Books.BookID _
Select Books
Me.BookBindingSource.DataSource = allBooks
Next I need to display all majors in a listbox. I would like the description to be shown however I am only getting the majorID to display with the code
lstMajors.DataSource = db.Majors
I have tried db.Majors.Description, however I am told then that Description is not a member of the LINQ table. and my final goal is to display all the books for whichever Major is selected in another data grid. This is what I am primarily concerned with right now. When using the SQLClient classes, I was able to create a string joining the tables (also had the description properly showing in the listbox, but that is of little importance right now to me). In the video tutorials I was able to watch whenever the tables were dragged from the database into the OR designer of the LINQtoSQL.dbml class file all of the associations were already there and the narrator only really had to do some drag and drop. Not only is drag and drop not working without these associations, but I'd much rather learn the code behind it.
I have a class that add extra information about a column for linq2sql (see code below) right now, I have to explicitly tell what column I want that info on, how would you put that code with a loop on every column in every table from a dbml file? I was doing my test on a very very small DB, now I have to implement it on a much more bigger database and I really don't want to do it manually for every tables/columns it will take hours.
how it's being used:
Partial Class Contact ''contact is a table inside a dbml file.
Private _ContactIDColumn As ExtraColumnInfo
Private _ContactNameColumn As ExtraColumnInfo
Private _ContactEmailColumn As ExtraColumnInfo
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I have a base class (ex: Class1) containing a list of another base class (ex: ClassA). Each child class of first base class (ex: Class1AA, Class1AB,..) containing a list of child class of second base class (ex: ClassAA, ClassAB,...)The client must never know which child class is using, then i don't think i can use generic for my bases classes.I try something like this and many more, but i always received errors..Imports System.Collections.Generic
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I have a main form, and some sub forms, and each sub form can have some sub forms. When I have multiple sub forms open, and I try to get data from the parent form, it returns the data from the wrong parent form.For example I have two instances of Mainform.subform running. If I do something like this in a child form of one instance of the subform. It returns data from the other subform.
dim l = Mainform.subform.listofdata
Edit:I am using visual Studio 2008. Winforms, form designed using designer. In my mainform I am doing this
Protected Friend frmMain as Mainform
frmmain = new mainform
In frmMain I am doing this
Protected Friend frmsub as new Subform'
frmsub = new subform
[code]....
I'm working with a class that inherits the XElement class.The new class is called MXElement.It adds some new functionality to it for navigating through the XML tree, as well as some more information regarding attributes, but that's not particularly important.My problem is that I have an XML Tree filled with XElement objects.However, when I create a new MXElement object from the XElement object before, it is just a copy of that object. This means that any changes that I make to this object will not effect the original tree.I suppose what I'm asking for is a way to build in the functionality for my MXElement class and keep references to the original XElement objects.If possible, I would really prefer to keep MXElement a child class instead of building a lot of extension methods for XElement.
View 1 RepliesI am using VS2008 and SQLite. I have created a database and several tables and am attempting to populate the tables with data from arrays.
The following code (example) works fine but stops after it inserts 30 to 50 records. I am running the VB code in debug mode and when it stops, I press pause to see where it is. It stops on "SQLcommand.ExecuteNonQuery()" and when I press continue (F5) it will insert another 30 to 50 records.
I do not get an error message. Is this a timeout issue? How do I keep the loop running to the end of the array?
Following is example code.
Dim
SQLconnect As New SQLite.SQLiteConnection()
Dim SQLcommand As SQLiteCommand
CODE:.....................
have a datagridview containing 2 tables left joined, so that:table1 LEFT JOIN table 2 ON table1.id=table2.idI get an error whenever I try to edit my datagridview."invalidOperationException was unhandled by the user codeDynamic SQL generation is not supported against multiple base tables."The error points to this line:
da.FillSchema(dt, SchemaType.Mapped)
da.Update(dt) << This line
'da = dataadapter
[code].....