I want to declare a variable to hold the query result from LINQ to SQL like to the following:
Dim query As IQueryable(Of Student)
If isNoUserName Then
query = From st In db.Students _
Order By st.AssignedId Ascending _
[code]....
Return query
Error : conversions from 'System.Linq.IQueryable(Of )' to 'System.Linq.IQueryable(Of Student)'.
How do I declare variable "query" to hold both data from "Student" and "User" tables?
Is it wrong? Please suggest me correct way.
Public Function ReadXML() As List(Of String)
Dim list As New List(Of String)
Dim xmlDoc As XDocument = XDocument.Load("C:\MappingFile.xml")
[code].....
How do I assign the query result to a variable.I am using SQLlite. Below is the code for retrieving password from the User Table. I need to compare the given password and the given password.
Dim i As String
Dim p As String
i = txtUserID.Text
[code].....
I have two module-level variables and Linq query. I want the results of the Let clause to change the global variables - is this possible?
For example:
Dim X As Integer = 0
Dim Y As Integer = 0
[code].....
I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
given this function:
Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _
[Code]....
instead of what I expected:
Select count(*) from remitline where lastname = "smith"
What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesI am getting the error:"Range variable 'sender' hides a variable in an enclosing block or a range variable previously defined in the query expression."for this
Imports System.Data.SqlClient
Imports System.Linq
Public Class Form1
[code]....
I can select any other item from the table without the error. "sender" has the same properties as "receiver" in the SQL table.
I have this LINQ query lq_customer_product which has something like this [code]I had a combo which contains the product_name get it from lq_ customer_product, means the combo has 5 item in it.when I select an item from the combo (let say i select prod1) the following should occur:[code]
View 3 RepliesI have to join two main tables, and I need to filter the results by elements in an ASP.NET web form. These filters are created on the fly so I have to use a lot of where extensions to filter the query. I want to execute the query with as optimized SQL as possible.
I am first doing a simple join between TW_Sites and TW_Investigators. Then there are two sub-tables that are involved. TW_InvestigatorToArea and TW_InvestigatorToDisease. While most of the where clauses are working fine, I have found a performance issue that won't be an issue right now, but will be an issue as the table gets bigger.
The arrays DiseaseCategories and DiseaseAreas would be the results of a CheckBoxList result.
Protected Sub LoadResults()
'Get Dictionary of Filters
Dim FilterDictionary As OrderedDictionary = Session.Item("InvestigatorFilterDictionary")
' Initialize LinqToSql
[code]....
I have a file txt file that holds 3 values each seperated by a space how can i assign each value to its own variable and use that for other things?
View 4 RepliesForgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
I am trying to run a query an Access db from VB. The general query which I want to run is
SELECT * FROM Patient WHERE Patient.PatientID = ?
or SELECT * FROM Patient WHERE Patient.PatientLname = ?
I tried using an input box which captured the user input and pass that variable to the query, but that failed. Then I read about writing a function and using that, however, I keep getting an error which says Function not defined, but when stepping through the code, it seems to work. Here is my function: [Code]
I've been making this BlackJack program for a school project
I have 52 image files, labelled from '_1' to '_52' in my resources folder, each number corresponds to a card.
My question is, how do I get a picture box to assign the correct resource according to a variable
So, say I have
"pictDealerCard1" -> picture box which displays the first of the dealers card
DealerCard1 = 37 -> random number generated through INT(RND() * 52)
and resource '_37'
[Code].....
I need to assign a varible in a while clause. I.e., i would do it in php like this: while (!is_bool($char=$this->getChar()) in every loop, the function would assign $char a value, the is_bool function would test it, and the code INSIDE the while clause would have access to that $char.
View 4 Repliesi would like to assign the value of a combobox to a variable and use this variable as a parameter on the insert statement.see code below,code 1 works ok,but code 2 brings an error relating to wrong datatype,i cant seem to find where the problem because i think i am doing everything right.
[Code]......
i would like code 2 to work so that i can assign the variables different values at different scenarios. column serialno is a foreign key from table Stock.
I want to assign a string value to a variable in the DataGridView LostFocus event. I found that I can't just do variable = "string value, it will give me the "Unable to cast object of type 'system.eventargs' to type 'system.windows.forms.datagridviewcelleventargs'" error.
The function created by double-clicking on the datagridview is:
Private Sub DataGridViewInvoice_LostFocus(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridViewInvoice.LostFocus
I'm trying to retrieve data from an access database, but I'm trying to do it all in VB. Basically I need to query the database, and I think I've done that correctly. But then I need to assign the value in a certain field, to a variable. So for example,
Dim email = orders.CustomerEmail.
How to assign a value to a variable.
Below is my current code:
Dim acc
As
New AccessDataSource()
accDS.SelectCommand = "SELECT TOP 1 orders.OrderDate, orders.OrderNumber, orders.OrderProduct, orders.OrderTotal, orders.CustomerName, orders.CustomerPostCode, orders.CustomerEmail"
accDS.DataFile = "~/App_Data/Database.mdb"
I get nothing but headaches when I try to update settings in the My.Settings class, or when I try to assign a newly assigned setting to a variable. Sometimes the settings update OK at run time; other times times they update only after the application closes; and other times still they appear to update at run-time, then when I close the program and reopen- they go back to the previous settings.This is how I assign a value to a my settings and how I assign a setting value to a variable.[code]
View 6 RepliesI'm new with vb.net my problem is how to assign field value from database to a variable here is my code
Call connectdatabase()
dim uname as string
dim pass as string
Try
sql = "SELECT * FROM user;"
command.Connection = conn
[Code] .....
i like to assign html codes to String variable
Dim code As String
code= " <meta http-equiv="Content-Type" content="text/html; charset=windows-1254"> "
i think i am getting this error because of double Quotation marks "character constant must contain exactly one character."how can i assign it to a string?
This is my first attempt at writing a program that accesses a database from scratch, rather than simply modifying my company's existing programs. It's also my first time using VB.Net 2010, as our other programs are written in VB6 and VB.NET 2003. We're using SQL Server 2000 but should be upgrading to 2008 soon, if that's relevant.I can successfully connect to the database and pull data via query and assign, for instance, the results to a combobox, such as here:
[Code]...
How do I execute a query so as to assign each field of the returned row to individual variables?
I would like to assign cboBegCust.SelectedValue to c and cboEndCust.SelectedValue to d
Dim c, d As String
cboBegCust.SelectedValue = "customer"
cboEndCust.SelectedValue = "customer"
[Code]....
I want to Assign the Value to Multiple Variable of same type in .net and that to in one line of Code.
View 6 RepliesI think I remember reading somewhere that it was possible to assign items to a variable if the item inherited from a base class, but I can't remember how.
I want to have a class that gets properties set and one of the properties is an error code property. I want to assign any exceptions that occur to the property, but it could be any type of exception. I remember that all exceptions inherit from the Exception class.
How can I assign an exception to a property based on the class it inherits from?
I have the following
Public Structure Foo
dim i as integer
End Structure
[code].....
is there any possibility to assign a value to a variable inside an IF condition in VB.NET?
Something like that:
Dim customer As Customer = Nothing
If IsNothing(customer = GetCustomer(id)) Then
Return False
End If
Any way to attempt to assign a variable within a data class or structure when I have the variable name as a string. Where would this be useful? Let's say I have a data class that exactly mirrors the columns of a table in a SQL database. This lets programmers easily interact with table row data as it gets passed around as an actual, specific object since Intellisense can enumerate the variables for them, etc.
However, populating such an object is tedious and repetitive--the programmer who creates the new object has to one by one match up all the members when reading from the SQL data adapter. It would be nice if they could somehow enumerate all the variables in that class and attempt to auto-assign the values from the database instead of having to build a custom population method for each new data class. A person could create a hash table or tree or something that pairs member names with actual objects.
I've just read [url]...
I'm wondering if it is a typo. Do they actually really wanted to say: the implementation of the JVM is free to instead of the compiler is free to.
and my second question is that do we have this issue with C#/VB as well? (in which the ""compiler"" is free to assign a value to a variable even before the variable is fully initiated/even before the constructor function of the class of the variable is fully ran.
Is it possible to declare a variable and to choose it's appropriate type during runtime?
it should be something like this (of course, the last line does not work):
'Determine what type of variable is needed later
Dim myVariableType As System.Type = System.Type.GetType("System.String", True, True)
'Create variable with needed type
Dim myVariable As myVariableType ' Should be a string variable in this case