Basically, I am trying to write a LINQ to Objects statement where the relationship is a grandparent, parent, child relationship. (You could also call it a Master Detail relationship.)
Dim coverages As New List(Of Coverage)
Dim coverage As Coverage
For Each rl In oClaimsPolicy.RiskLocations
[code].....
How do I correctly setup a Child Parent relationship in code using VB 2008?Hendri Bissolati (Novice programmer)
View 3 RepliesI am working on my final project and I need to have 1 MDI Form. For the life of me I cannot figure out what to do. My book mentions doing this:
Dim childForm as New ChildFormClass()
childForm.MdiParent = parentForm
childForm.Show()
When I put that in the Parent form it doesn't like the ChildFormClass(). I wouldn't think it would be too hard to make a parent child relationship? I have tried looking for the MdiList property but I cannot seem to find it. I think I need to have some menu items to have a child form. If there is a way to have an MDI form without that I would like that. Does anyone know a good tutorial that explains creating MDI forms well, and what to do/put in the parent and child forms code?
Basically, I am trying to write a LINQ to Objects statement where the relationship is a grandparent, parent, child relationship. (You could also call it a Master Detail relationship.)
In Legacy code here is a simplified version what I am trying to accomplish.
Dim coverages As New List(Of Coverage)
Dim coverage As Coverage
For Each rl In oClaimsPolicy.RiskLocations
coverage = New Coverage
coverage.Level = "Location"
[Code] .....
If is it not clear one Location can have many Items and one Item can have many Coverages. I basically want to list the items and show the relationship between grandparent (Location), parent (Item) and child (Coverage).
I know I can set IsMidContainer in forms for parent-child relationship forms. I just want to know if the parent form could be a panel. If so, how can i do it?
View 1 RepliesI have 3 tables:
CustomerType
CusID
EventType
EventTypeID
[code]....
Then I want it to automatically insert data into CustomerEventType table based on the last EvenTypeID data that's just inserted and the checks of the CusID that is using CheckBoxList1 bounded from CustomerType (Suppose there are 2 IDs. )After I Click on Insert button the data in EventType table and CustomerEventType table should be:
EventType
EventTypeID
1
CustomerEventType
[code]....
The only question that I have is, what should be the code behind the insert button using VB.NET LINQ-to-SQL to get this result?
C# or VB.NET is fine. I'd like to count number of people for each country from the following tables with LINQ to SQL I have two tables, one is Countries and other is People. It's one to many relatoionship from Countries to People. ountries table column:CountryId,CountryName People:PeopleId,FullName,CountryId (a primary key from Country table and allowed null) I want to count how many people each country has and get something like the following result that shows only the country that has people. Because there are some countries that have no people in the People table.
[Code]...
I created a dataset.xsd and it contains two table adapters and these table adapters use stored procedure for select.in my vb form, i get value in text box and then fill table using tableadapter and pass parameter to sp. Till this point everything is working fine. Now these tables have relations and i want to create relationship and show the data from child table on basis of master table. How i can do it?
Example
Me.MasterTableAdapter.Fill(Me.dataset1.spMaster, 1) --1 is parameter which is passed to sp
Me. ChildTableAdapter.Fill(Me.dataset1.spChild,1) --same parameter is passed to child table.
Now i have the records in spMaster and spChild. how i create the relationship so that when i move thru Master the child have corresponding records?
I have a form that is set up like a master/detail form - fields on top with a child grid below. The difference here is that the child grid is reflective of a recursive relationship. That is the ID of the master has a one-to-many relationship with another attribute called "parent." the child grid displays all the children for that parent. It works properly except when a new record is being added to the master.My issue is that when the user clicks on the Add New button, the child grid then displays all the available parent records in the system instead of an empty grid. Once the new master (parent) record is saved, the grid reverts to proper behavior.Thus, my question: How do I prevent the child grid from displaying all the parent records when a new master (parent) record is being added?
View 1 Replieslong story short, I have created a ListView type control, using UserControls for the parent control and the ListViewItems. Most the of the control is written and works fine, right up to the point where I tried to replicate the 'Control.SelectedItems(0).Index' property and the 'SelectedIndexChanged' event.
Each child object knows its index value, and could pass this value via the SelectedIndexChanged event (assuming this is how it works in a normal ListView control -- user clicks on an item, and that item fires an event updating the selected index value in the parent object).
How does the child object raise an event in the parent object? I have a feeling this could be done with Delegates, but I'm still learning about their usage.
I am developing a new class which is a control that inherits from the "Panel" class. In this new class, I have three objects that are generated every time I create a new instance of the class. For simplicity, I will call this class "garage" and the three objects "BMW," "Lexus," and "Acura." So each new garage has three types of cars.
how can I share a variable from the Parent class with all of it's child objects? i.e. The garage has an array variable called "tires" which all three cars use. Rather than create each car object with the tires parameter, I would just like to keep the tires parameter in the parent class so that all my child objects can use it. I know that normally the parent class should provide the child class with all information when creating the child but it would seem redundant to pass the entire tires array each time since all three cars use the same tires and the tires object never change.
I use Visual Basic 2008 Database is Mysql Three tables:
[Code]...
I remember we were taught BASIC (Beginner's All Purpose Symbolic Instruction Code) language in school, when we were in 5th grade. It was purely in DOS-Mode and we basically used it for drawing. Then I learnt Visual Basic 6.0 quite a few years basic. I neve found a similarity between them
View 11 RepliesI have two tables which need to be connected using a one-to-one relationship. In SQL Server 2005, how would I add this relationship to the database diagram, do I just leave the relationship blank? Is there any pre requisite queries I have to add? How do I connect these tables in VB? .. the same way I would connect a one-to-many?I need the Student table to be linked to the Class Table where One student can be in only 1 class.
View 10 RepliesI have a table (Projects) which is linked to projectVersions on projectID..projectVersions contains several columns on which I'd like to filter a returned project (and associated projectVersions) list. For example there is a "capacity" column and a "country" column. I am doing a filtered list of projects on one page and I'd like to include all projects where any one of the associated projectVersions has a capacity of 750ml and a country of "France" for example.It may be that a particular parameter is not set and so I pass a zero to indicate not to filter on that.I guess this needs some kind of subquery as when I try and do something like this: [code] it doesn't work as the "xxx" bit, being one-to-many, expects me to specify an item to get at the entities within and yet I want to query where ANY of the associated versions match one of the criteria.
View 1 RepliesMy issue involves relationships and cascaded effects between properties, and I'm wondering what best practices are on this.I have a class that contains a list of varying length of numbers. When editing the list, sometimes the user prefer to set a TargetSum, so that the program enforces the list will always add to this sum. I am accomplishing this by programmatically setting the final element in the list such that list sum = TargetSum. For example, if the user chooses to UseTargetSum, then sets TargetSum = 10, then creates a list of length 4, and enters 1, 4, 2 for the first 3 elements, then the final element is programmatically fixed to 3. The user cannot change the final element themselves.
I do this behind the scenes by handling all necessary events, such as a list element value change, list length change, and the UseTargetSum option change. For each event trigger, it recalculates the last element's value.It works but then there was a bug when loading saved data. If a list is loaded by sequentially adding the elements, the handlers modify each entry. Regarding the example, when the first value of 1 is entered, the handlers say "a value was just added, the sum should be 10, there is currently only one element, so it needs to be 10". So the first element gets changed to 10 behind the scenes. When the second element is next added, the handlers say "a value of 4 was just added, but the first element is already 10, so it should be zero." At the end of the load, the final list reads 10,0,0,0 instead of 1,4,2,3.
I know it is possible to rearrange the load procedure such that I get the correct list. For instance, I could avoid enabling the TargetSum event handlers until after all the data is loaded. The list would first be created as 1,4,2,3 and then the handlers would change nothing.
But this experience makes me wonder if I am opening the door for other sneaky side effects. It seems you should be able to load data without worrying too much about an implicit ordering. It also seems unusual to have "cascading" effects between class properties. Is there a more accepted approach?
The other alternative I'm considering is to only enforce TargetSum only inside UI forms. Ie, when you know it's a user making the change, then enforce the TargetSum, but otherwise leave the core class logic alone.That way database loads, etc, are left unaffected. But I guess the downside of not having ubiquitous enforcement is that opens the door of incorrect sums via some unforeseen complication.
I have made a small "front-end" application for an Access databasefile.
I set up 3 tables with relations in Access, and added the database as a datasource in my project. I have done no database programming, and the app has worked nicely for about 2 years. It's a simple master-detail form with 2 datagridviews dragged from the datasource window.
Yesterday I opened the project to add a new form. The form is just a "setttings form" with no database activities.
When I press F5 - the main form do not start, and I get the error message "DataMember property '{0}' cannot be found on the DataSource." - where the property name is the name of one of the 2 relationships in the datasource.
Im would like to create relationships between my tables from different database. im using VB 2008 and SQL 2008 as my database. Is the relationships should be made on my database itself or tru coding in my VB? If either which how can i do that.
View 2 RepliesHow do we create relation ships between tables using a sql query?im using MS Access and VB.net.
View 2 RepliesI cannot figureout to which class ItemStatus should link to!please refer to my blog in the following link to detail description of the issue
View 2 RepliesI'm using a dataset class written by others who have defined the foreign key relationships between tables using the tools in the schema diagram. I'm binding the dataclass to a windows form. I'm running into an issue where I have an existing header record and I'm trying to insert data into a child table via a grid programmatically. The child table contains all keys for data. As the grid is bound to a binding source, I'm simply adding rows directly to the grid programmatically.
When I attempt to save the data, I get the error ForeignKeyConstraint FX_Activity_UserRoleActivity Requires Child Key Values (4) to exist in the parent table. The value (4) is one of the foreign key values and it does exist in the parent table. The error occurs when I tell the bindingsource associated to the child table on the form to EndEdit. Looking at the XSD file for the dataset, both foreign keys are set up for 'Both Foreign and Key Constraint' with Cascade set for both update rule and delete rule. Accept/Reject rule is set to none.
Running a SQL trace, I confirmed that SQL Server is not generating the error, so it is occurring on the client application somewhere. First what does the error actually mean? Second, does the configuration of the foreign key relationship in the dataset's XSD file have anything to do with it? If so how should the foreign keys be set up between the tables? If it isn't how would you go about troubleshooting this issue as stepping through the code ends with the .EndEdit call to the binding source.
StudentId is a foreign key in StudentSubject,What I want know is how do I illustrate the relationship between the two tables is many to one
StudentSubject
StudentID Subject
148 Art
148 History Of Art
145 English
145 Poetry
128 Chemistry
128 Physics
128 Biology
123 Math
StudentLocation
Student RoomNumber
123 1a
145 3b
148 4c
128 2a
If I a many-to-many relationship between Users and Roles and I have an instance of a User entity and several Role Ids can I insert a relationship between the two types of entities without having any other Role data and without doing a select on the Roles first? Update:
I might not have been clear enough. I don't have an instance of a Role, only the role id. Is it possible to create the relationship between User and Role without filling a Role object from the database first?
connection here and declaration of variable
Dim i As Integer
Dim chk As CheckBoxList
chk = CType(Me.FindControl("chkBx1"), CheckBoxList)
For i = 0 To chk.Items.Count - 1
[Code]...
I am trying to input value to AppSchedNumber into my AppInfo table which is the primary key of my AppExamSchedule (auto inrement). The problem is I can't insert on my AppInfo because my AppSchedNumber on my AppExamSchedule should be the same.
View 1 RepliesI am using VS2008 Standard, Access 2007 and VB.net. I have an Access db with a Membership table, a DuesPayment table and a table linking the two together.
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1) In VS I have a single form (frmMembership). I used the Data Sources window to create a single datasource containing the tables tblMembers, tblDuesPayment and lktblMemToPay. from the 'Data Sources' window I drug tblMembers, as text boxes, to the form. I drug tblDuesPayment to the form as a DataGridView.
I right-clicked 'dsMembership...Edit in Dataset Designer' and checked that the relations between the three tables was as shown above. I left all other settings as they were created by VS.When I execute the app I get the member information as expected and can use the TblMembersBindingNavigator to step through the members. The DataGridView, instead of showing dues payment information for the member showing on the form, shows ALL of the dues information for ALL members does not exhibit any relationship between tblMembers and tblDuesPayment.
2)I also tried creating a dataset for tblMembers only. Then I used 'dsMembership.Edit in DatasetDesigner' window to create a TableAdapter for tblDuesPayment and lktblMemToPay. I got the same results.
3) I tried various other combinations, like creating TableAdaptors for tblMembers and a TableAdaptor for a combination of lktblMemToPay & tblDuesPayment.
how F# is a language which allows you to approach problems in a different way than in C#/VB.NET, i.e. instead of "pushing bits around" you "chain together data transformations", and that how F# will "become like XML", something that you use in addition to your language of choice (C# or VB.NET) in order to solve certain problems in a more efficient way.This got me to thinking about the relationship of the .NET languages, here's how I understand them:C# and VB.NET are syntactically but not substantially different, i.e. a C# programmer would not learn VB.NET in order to "approach problems in a new way"however, a C# or VB.NET programmer would learn F# in order to "approach programming problems in a functional way"but what about IronPython and IronRuby? Chris mentioned that "F# learned a lot from Ruby and Python" so I would think that F# has a similar relationship to IronRuby/IronPython and C# has to VB.NET. However, a little googling around tells me that IronRuby and IronPython are both built on the DLR but F# is not.
How are the relationships between F#, IronRuby and IronPython to be best understood?
Can we call firewall an interface?
View 1 RepliesI'm using VS2008 with SQL Express 2010. I've a one to many relationship and a form with these two tables on. I'm using the BindingNavigator toolbar and when I press the + button, a new record appears. However, I have to press the save button and save the parent data (which is in Details view) before I can add any data to the child table (which is in a DataGridView). Once I've clicked save, then I can add child data no problem, then I click save again and all my data is saved.
Is there any way to save all the data at once? If not what is the best practice for telling the user when to save? Should I make the child data grids invisible until the user clicks save?
How would I connect different tables with each other in vbnet2008 which ive connected by the database wizard? Also I want to connect this table for the search purpose. I filter it by Name which is in my personal_informationtbl so the rest of the table must show the related information about the Name that I've searched. So meaning if I just search by name it shows related information from the records not just from the personal_informationtbl but fill the other tables with the related information.
View 2 Replies