Processing an XML file with LINQ to add records into a table in a SQL Server database via a data context. As we are adding records we need to assign the parents in various other tables. Most of the time we can find the existing parent and use it but sometimes we will need to create a new parent.Thought we could do this like this:
Dim defaultPub As publication
defaultPub = New publication With {.name = e..Value}
Dim pub = _Data.publications.Where(Function(s) s.name =
i have 3 tables in ms access that is patient , NOK,and admission they have related fields, i am using vb 2005. when i delete a record from the patient table i want the related records from the other tables to be deleted.
I am trying to accomplish the following: SELECT Table1.prod_code, SUM(Table1.prod_bal) AS TotalProdBalance FROM Table1 LEFT OUTER JOIN Table2 ON Table1.prod_code = Table2.prod_code WHERE Table2.prod_code IS NULL GROUP BY Table1.prod_code HAVING (SUM(Table1.prod_bal) <> 0) How to translate this to Linq using VB.net syntax?
Using a datagrid, binding to one table, and related to one combobos, I cant update records, cause gives me a violation error. I'm not changing the primary key, so, I dont undersatnd cause this happen. I prepair a example of this error, and it was attached to this message.
I've got a problem with Linq in VB.NET.I've created a .dbml file from my db, and everything looks good - relation "arrows" between tables are visible, etc.But when I want to use simple query (taken from 101 Linq Samples by MS):
Dim q = From h In dc.Hours, w In h.WorkType I receive an error:
I have built a database structure that represents a category tree to help classify some of the data we have stored. The implementation is that each record in the Category table has a nullable foreign key back into the Category table to represent the parent Category of this category (one-to-many), essentially allowing for subcategories within a broader parent level. There is a CategoryMembership table that links a record in the Item table to its respective Category (many-to-many). I have created the DBML for this database, and it has a member access structure that includes the following:
I have two tables Products and Categories with a many to many relationship. I am trying to copy the categories linked to one product (OriginalProduct) to another product (newProduct). The problem is when I execute the SaveChanges() method, I not only get the records in my linking table, but it also creates another copy of the categories in the categories table. I've tried this in many ways but here are the last couple that I've attempted:
' Copy Product/Categories For Each oneProdCategory In OriginalProduct.Categories Dim relatedCategory = _productContext.GetObjectByKey(New EntityKey ("ProductInfoEntities.Categories", "RecordId", oneProdCategory.RecordId))
I asked on SO a few days ago what was the simplest quickest way to build a wrapper around a recently completed database. I took the advice and used sqlmetal to build linq classes around my database design.
Now I am having two problems. One, I don't know LINQ. And, two, I have been shocked to realize how hard it is to learn. I have a book on LINQ (Linq In Action by Manning) and it has helped some but at the end of the day it is going to take me a couple of weeks to get traction and I need to make some progress on my project today.
Click HERE To see my simple database schema. Click HERE to see the vb class that was generated for the schema.
My needs are simple. I have a console app. The main table is the SupplyModel table. Most of the other tables are child tables of the SupplyModel table.
I want to iterate through each of Supply Model records. I want to grab the data for a supply model and then DoStuff with the data. And I also need to iterate through the child records, for each supply model, for example the NumberedInventories and DoStuff with that as well.
For the record I have already written the following code...
Dim _dataContext As DataContext = New DataContext(ConnectionStrings("SupplyModelDB").ConnectionString) Dim SMs As Table(Of Data.SupplyModels) = _dataContext.GetTable(Of Data.SupplyModels)() Dim query = From sm In SMs Where sm.SupplyModelID = 1 Select sm
This code is working...I have a query object and I can use ObjectDumper to enumerate and dump the data...but I still can't figure it out...because ObjectDumper uses reflection and other language constructs I don't get. It DOES enumerate both the parent and child data just like I want (when level=2).
How can I use Linq to SQL in Vb.net to combine the records of two tables into a datagrid such as shown in this example:Assume i have two tables tbl1 and tbl2
way to write the LINQ query. The parent class is simply a student's name and a list of test score data. The child class is a single test score datum. I want to find the worst (or best) score out of all of the TestScore values and then identify the student who had the best score.
Dim query = From s In studentList _ Where s.ScoreList.Select(Function(d) d.TestScore).Min _ = studentList.SelectMany(Function(g) g.ScoreList).Select(Function(h)
Have seen some solutions for C# but do not know how to solve the issue in VB.NET.
Query:
Dim Query = (From t In myEntities.Bookings Where(t.Ref = Someid) Select t.People).Sum()
t.Ref field is an Int and so is t.People.
The SomeId value is the primary key of the related table. This issue is that there will not always be records in the Bookings table with a Ref value of Someid - so the query throws the following error.
I have seen others have got around this problem with catching the error, but from reading up on this and as per the error information it seems there should be a solution (in VB.NET) to cast the query or some of the fields in the query to nullable types?
Error is as follows:
The cast to value type 'Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
I've got a table that caches calculated values for certain dates. I want to use LINQ to select all rows where the calculated value fields are null.But when I use isNothing I get an error that LINQ can't translate this into T-SQL. Is there a way to select null values with link, like this...?
Dim var = From rec As Record In myDataContext.Records Where IsNothing(rec.calculatedValue) Select rec
Other posts on stackoverflow mostly discuss how to avoid or check for null values with LINQ.
Note: I can't just set cacluatedValue's default to -1 to flag records whose calculated value has not been set (and then select those records) because I run queries that sum/average the calculated values. Selecting nulls seems cleaner and less bug-prone.
i can't seem to add to records on the one row i get the error saying "Column count doesn't match value count at row 1"but it works when i only add one record.
Imports MySql.Data.MySqlClient Public Class PatientInfo Dim ServerString As String = "Server=sappracticedb.db.7735192.hostedresource.com; User
I need help with adding a record to a database.I have a database with multiple tables. How do I add a new record to one of the tables without using the BindingNavigator.Lets say the table's name is tblDetails and the fields are:NameSurnameCellAddressI have a number of text boxes on my form:txtNametxtSurnametxtCelltxtAddressI want to add the details from the text files to the table and a new record.
There is one-to-n relationship (foreign-key relationship) between tables As and Bs. Every time a new record is added in As, a trigger "after update" in table As creates n records in table Bs. There are two Linq-to-SQL classes A and B representing the tables As and Bs respectively.The class A contains Bs property an EntitySet(of B). Similarly in class B, there is a property A, an EntityRef(of A)
[Code]...
When above function is executed the result is always 0. Whereas there are six records new records has been added to table Bs every time the above function is executed.
I'm using visual basic 2008 express edition by linq to sql for my database operation such as edit records. I did not use any sql server but I'm just using the built-in sql server within the visual basic 2008 express. I tried to revised the codes, no error in syntax but there's an error at runtime and it pops-up a window message saying its error message. What I want is to edit the records which were retrieved from the database into the text-boxes and when you click the button5 whatever the new value on the text-boxes should replace the previous one.The Account field is the field in my Table1 in memrec.dbml which I set up for primary key is true and the rest of the fields are false in its primary key.[code]...
Is it possible to do a multiple records editing by linqtosql method in one click event? What I've been trying to do is to edit all the names in the table which are having the same account number. I was able to edit but only one name has been edited and the rest are not.
The codes I used. Private Sub Button2_Click(------------) Handles Button2.Click Dim accnt As String accnt = Textbox1.Text Dim db As New memrecDataContext() Dim editrecord = From mem In db.Table1s [Code] ......
Why is it these codes could only edit records in one datarow?
I'm using visual basic 2008 express edition by linq to sql for my database operation such as edit records. I did not use any sql server but I'm just using the built-in sql server within the visual basic 2008 express. I tried to revised the codes, no error in syntax but there's an error at runtime and it pops-up a window message saying its error message. What I want is to edit the records which were retrieved from the database into the text-boxes and when you click the button5 whatever the new value on the text-boxes should replace the previous one.The Account field is the field in my Table1 in memrec.dbml which I set up for primary key is true and the rest of the fields are false in its primary key.The code below still found an error when you run the program and it pops-up a window which says:
NotSupportedException was unhandled - Sql server does not handle comparison of NText, Text, Xml, or Image data types.It highlights a yellow background on the line:
db.SubmitChanges()
These are what I see on each field's property on Table1 in memrec.dbml property window:
Access - Public Type - String(System.String) Server Data Type - Text[code]........
Here me again since i'm done now in Sign Up form.Another database coding to add a records..i try to copy the same code with my sign Up form to insert a records....to input a Litre and Price. is this correct?
Public Class frmGasolineSales
Private Sub slc(ByVal sender As System.Object, ByVal e As System.EventArgs) Dim thistabcontrol = CType(sender, TabPage) Select Case (thistabcontrol.Name) Case "TabStation1"
I have been trying for a month to get a row added to an Access database and can not do it. I have the databindings all set and can select different records, but can not add a new one. I have tried BindingSource.AddNew.row() but can't figure out how to add data to the new row, nor does it show in the database.
I have tried
Dim ds As New myDataSet '<---Change this to the dataset name on your form Dim dr As DataRow dr = ds.Tables("Students").NewRow
[Code].....
But that doesn't do anything at all. No data added, no errors. I have tried updating a datagrid to be told it can't be updated when bound. I look on google and nothing seems to relate to adding data to an access database when bound to the project through the datasource wizard.
I have the following code which I hoped added a row to my DataGridView and also a record to my database. It does the first part, but not the second. Dim row As DataRow = Me.CCLogDataSet.tblLog.NewRow() row("cc_log_contract") = Me.txt_Log_Add_Contract.Text row("cc_log_registration") = Me.mtb_Log_Add_Registration.Text.ToUpper() row("cc_log_milage") = Me.txt_Log_Add_Milage.Text [Code] ..... It seems to be storing the data in memory? As the data in the DataGridView is persistant, even after a Relaunch of the application. However, why I query the database, there are no records in it.
I'm trying to add a record through access. Below is my code. My problem is that when I add a new record, it adds to the database fine, and goes back to the first record like it should, but when I then scroll through using the BtnNext (button), it replaces the last record with the first record for some reason. This is the UI of it [URL]. A bit of further explanation, I'll have 3 records, IDs 1,2,3 respectively. I go to add another (with its ID as 4). When it's added, the program displays ID 1 as it should. It then goes 2 then 3, but instead of 4 as the next one, it displays 1 again. So 1231.
Here's the Public Class ViewStudent Dim con As New OleDb.OleDbConnection Dim dbProvider As String Dim dbSource As String Dim ds As New DataSet [Code] .....
I am using OLEDBConnection and OLEDBDataAdapter and connected to the MS-Access databasehow can i add the textbox value to the table in database on a button click and want to display it in datagridview??
I am developing an application in vb and access my sql query in access please have a look.
str = "insert into details values('" & username & "','" & CDate(date1) & "','" & time & "','" & PrinterName & "','" & noofpages & "','" & _ Message.ToString & "') WHERE not exists (select * from details where Date1 = " & CDate(date1) & " And Time = '" & time & "')"
I was trying to check the database before adding the records For some reason its not working Query input must contain at least one table or query Is exists allowed in access or is there any other keywords in access?
I'm trying to read the records into a combobox from the database without any success. There is no problem with the connection, but something seems wrong with my coding. Perhaps someone could tell me what I'm doing wrong.
I am trying to add a player registration form to a textfile. And i have a few problems.One of these is that when adding to the textfile, it isnt recognising the selected value in a checkbox (checkbox is used to distinguish between a goalkeeper and an outfield player). Can you tell me what should I be writing to make this happen, - "chkGoalkeeper.??? = "" "
One of these is that when adding to the textfile, it isnt recognising the selected value in a checkbox (checkbox is used to distinguish between a goalkeeper and an outfield player).Can you tell me what should I be writing to make this happen, - "chkGoalkeeper.??? = "" "
This is the hardest part of LinqtoSql database handling operations in visual basic 2008 I ever encountered,w/c is the update operation cause Ive been posting this thread several times from the other forum site but noone yet was able to answer my question,examples were given but its not efficient cause it won't specify based on the codes i gave and i know its not easy but im still hoping that one of the answerers of this forum will be able to resolve this particular linqtosql operation codes. I used textboxes in manipulating all data into the database such as displaying records, adding records, & updating records, basically I used with textboxes in doing those database operations. I will give you 3 block of codes w/c corresponds those database operations I used and differentiate from each other inorder for us to determine why one of them has no progress or won't do its operation w/c is the update operation...
*************Block of Codes#1(Adding Records)************* Private Sub Button1_Click(------------------) Handles Button1.Click Dim db As New memrecDataContext()
[code]....
I would like you to identify,differentiate, or troubleshoot the block of codes#3, or anyhow, why it has no progress at all or it won't edit and change the records but it runs and no error in regards with its code, and the other 2 blocks of codes were able to successfully do its operations.I was just wandering why only the block of codes#3 is not doing its operation successfully when you change the record being displayed in the textbox.Is there a possible way to edit records in the textboxes?If there is.... Is it possible to debug the block of codes#3 to successsfully do its operation? If you could possibly give an example,can you based it on the block of codes#3?
