Checked out the video on MS website by Beth Massi and downloaded the project.
One query she uses this statement,[code...]
I'm I missing a reference or something? This is an Access DB, does that make a difference?
I have been looking into dynamic querying of datasets and the use of copytodatatable() for a project. I have seen in alot of forums that the copytodatatable functionality is unusable as it was removed. have an example of a dynamic Linq query being loaded into a datatable.
View 1 RepliesI have this LINQ statement [code]...
Is there any way that I can use if/iif within select ?
If I have a datatble column set as int16 but rows can contain null values for this column. How do i write the linq query. I keep getting an error null value exception. Dim query = From n In resultstable.AsEnumerable Where n.value is dbnull.value does n't work.
View 6 RepliesI just upgraded a project from VB 2008 to VB 2010. Before, the project did not use LINQ. I have started implementing it. So, I have updated the target framework from 2.0 to 3.5, and added a reference to System.Core, and imported the namespace System.LINQ to the entire project and also imported System.Data.LINQ into the form I'm working with (because it was not available in the list for Imported Namespaces in the references tab).
It's not throwing any errors now, but my IntelliSense is not working for LINQ stuff.
For example... I write this:
[CODE]....................
Then, if I type S. on the next line, the IntelliSense doesn't grab what it should for S (Only get Equals, GetHashCode, GetType, ReferenceEquals, and ToString, instead of the options I should get like Count, First, FirstOrDefault, etc...). If I Type S.First. then its the same thing, no IntelliSense that lists the available fields for S, just the standard options (Equals, GetHashCode, GetType, ReferenceEquals, and ToString). I should be seeing my column names in my table when I type S.FirstOrDefault.
So any ideas what is going on? When I type the code, for example, MessageBox.Show(S.FirstOrDefault.FirstName), it works perfectly. But it doesn't change the casing of the text (so it would read s.firstordefault.firstname) and no intellisense while doing it. But no errors. BTW - Everything works perfectly when creating a NEW VS 2010 application, it's just my projects upgraded from Visual Basic 2008 that have this issue.
I have a taskfactory application that generates new tasks where a task is running a project exe file that involves a lot of classes. Part of the task process involves declaring a dataset and adding a single datatable to the dataset which is then populated with content from results of a sql query. This datatable is then used in the next class and involves iterating through the table and deleting the rows it has already used. When initiating a new task I assume that it will declare its own datatable and dataset but not sure if this will work.
View 2 RepliesI have 4 ComboBoxen and 1 DatagridView into one Form. I make a code, for binding with 5 tables, each is own dataSet and dataAdaptor Is it possible to use one DataSet and one DataAdaptor for 5 Tables, so my code become shorter.
I think the solution is a SQL SELECT query, but i dont no for sure.If it is a SELECT query, ore something else, cane anybody help with make the code i need.
[Code]...
So I'm developing a program were, given some data by the user, the prorgam inserts some records into a database. To insert individual records in different tables I use either the standard INSERT method provided by the Table Data Adapter or a custom Insert Method when I want to insert something slightly differently.Sometimes the user would press a button and an operation where different records in different related tables are inserted. Since each Insert is handled individually for by the DataAdapters of each table, how can I manage to bring the whole thing to an atomic transaction way? I mean, let's say for example the User inserts a new Document in the system, the document has one or many Editions. How could i do something like: if the document was not created properly, then do not insert the editions.
View 2 RepliesI have an existing system that uses an ODBC connection to connect datasets to a SQL Server database. I want to conevrt these to use an OLEdb connection.
View 4 RepliesIm just starting to develop an application using a SQL Database as the main datasource. Now im wondering is it better to use the in-built dataset adapters or write the querys yourself?
If its better to use the pre-generated scripts by using the Datasource UI, How can i use these datasets on a JOIN query?
Example Join
SELECT column_name(s)
FROM table_name1
JOIN table_name2
ON table_name1.column_name=table_name2.column_name
Im currently making a program. It loads data from database fields into an combo box. Everything works so far, It just seems to be a mess. Do i need to have all the datasets and data adapters? or can i get away with just using 1 of each. It seems like im doing it wrong, and although it works it seems like a difficult and messy way of doing it.
Also i would like to assign the firshermenID to a variable depending on the fisherman name that is selected in the combo box. When button is pressed: id = fishermanID of the current fisherman (cmbFisherman.text)
[Code]...
I just read this post url...Post #2 by jmc states indicates the use of Entity Framework instead of typed datasets.when jmc says something I usually pay attention. I have a large app that I've been converting from VB6 to .Net and I've used mainly typed datasets.It's a single user app that uses an Access database. I'm have no problems retrieving the data from a table or multiple tables and I'm very happy with its preformance.Is it worth scapping what I've done and learn how to use Entity Framework? I should add that I'm near the end of my programming career not the beginning.
View 4 RepliesIn a typical session with the program I'm writing, the user needs to be able to access the data in 1 to 500 (maybe) tables (but always only one table at a time). Up to now I've been creating these single table datasets dynamically, as and when required.I've now come across the distinction between typed and untyped datasets (where typed seems to be the recommended option). It seems, though, that typed datasets are created at design time only and not dynamically. Is this correct? Are all of my dynamically created datasets therefore untyped?
View 12 RepliesIn proper sql my query would be something like:
select c.id, c.name, count(i.id)
from cats c, items i
where c.id=i.catid
[code].....
THE CODE IS :
var query1 = ((from c in dt.AsEnumerable()
orderby c.Field<int>("1") descending
select c));
var query2 = (from c in query1.Take(10)
select c);
[Code]...
I need to create an application that is able to modify the XML elements value.I have an XML file which was created by another to be used for flash movie which has the following layout:
<?xml version="1.0" encoding="utf-8"?>
<games>
<game>
<gameName>Cowboy</gameName>
[code]....
As you can see there is this string "™" on <gd02>. My question is, whenever I save the file, the code changed to "TM" which is fine for most cases. But I need it to stay the same because apparently flash will not display the superscript "TM" if not using the code. How can I do this?
I need help on how can I transfer a query from Access to LinQ that calculate the average in time per transaction during a given date.the working Access query is:
Avg(DateDiff("s",CVDate(Format([start_time],"hh:nn:ss")),CVDate(Format([finish_time],"hh:nn:ss")))) AS Expr1, Format([Expr1]3600,"00") & ":" & Format(([Expr1]60) Mod 60,"00") & ":" & Format([Expr1] Mod 60,"00") AS format
How can I port this to LinQ?
I have an array of approximately 1000 classes. All of these classes must have one of their properties changed to the same value. I need this to be as optimized and fast as possible.
Would LINQ be faster than a for-loop? Any other ideas for faster execution?
Is there a way to use LINQ to filter a DataTable for rows that contain particularcharacter but in a "Accent Insensitive" way? Search over the web I came with something like this:
Dim dt As DataTable = CType(BindingSource1.DataSource, DataTable)
Dim SearchVAlue As String
SearchVAlue = "e"
[code].....
I am trying to read information from a text file(.txt) using LINQ.I can't use a list box of predefined continents that someone can click on and it will bring up data from that continent.It will work if I let the countries fill the list box from the text file but then if I have two people from England my list box will display England more than once.For example my UN.txt file that is in my debug folder: [code] So I guess I have two different questions: 1. Is there anyway to stop the duplication of the continents as shown above? Can I pre-fill the list box with the continents and not have to fill it from what's in the data file?
View 14 RepliesI'm having trouble figuring out what to do with the bolded part, when there are no nodes to return.If there are no image tags inside the <images> tag, i get an "Object reference is not set to an instance of an object".I have been searching and searching for an answer but can't find one.
Dim orders = From o In xmlLinq.Descendants("order")
Select New With { _
.orderID = o.Attribute("id").Value, _
[code].....
I'm really struggling with this. I have two XML files. The first one has items, and then sub elements for properties:
[Code]...
So I have a query I'm doign where, at the moment, the places to search are set in stone, but the values that maybe be searched for is variable.Right now, I have a drop down menu that allows you to choose a character class. This limits the items to a specific class. Then I can filter on text from a textbox.
However, each item in the list has a source, based on the book it is published in. I want a user to be able to choose several from a checkbox menu, then pass those values for inclusion in the criteria for finding items.
The problem I'm having is finding the most concise way to do dynamic WHERE clauses. There are several examples out there, and even a couple don't seem to want to do exactly what I'm doing, and I'm having trouble determining if it will work for me.
After being quite sick of the my.settings-file behavior, I started to create an XML-file (with unique values). Now this works great!!! All my settings, connectionstrings, etc are loaded from an external file and won't be overwritten by the app. itself. But I was wondering how do I save a value/setting? Simple example:
HTML
<test>
<country>Holland</country>
[code]....
read the XML and node:
vb.net
Dim readXML = Xelement.Load(Application.StartupPath & "XMLFile1.xml") ' check if the node isn't empty (crash) If readXML.Descendants("country2).Nodes.Count > 0 Then Textbox1.Text = readXML.Descendants("country2).Nodes(0).Tostring() Else
[code]....
I'm trying to work with an ODBC driver for Interbase in VS2008 (vb). I succesfully inserted the data tables I want to use in the project datasource. Then I want to add some rows in one of the tables of the datasource. I used myDataSet.addTABLENAMErow(field1, field2, ...).The compiler gives me no error, but when I open the database with InterbaseConsole, the line I've add is not there. Do I do something wrong? Must I open/save the database (how do I do so). I've tried meDataSet.AcceptChanges whitout result.I'm not used to work with Datasets and tables...
View 1 RepliesI am working on an application in which i need to use reporting. i have used LINQ to entities and MS SQL server as database in my whole application. Now when i started working reports i noticed that crystal reports or no more included in visual studio. i downloaded it separately and installed it. i have also designed my report successfully but the problem is that how would i use LINQ with it?? I translated my linq query into datatables and it worked but the problem i am stuck at is, my report is based on two tables, after translation i am able to see records of first table but not the second one.
View 1 RepliesI'm trying to obtain name/value pair of enumeration typed into text box with LINQ. It's OK with name, but when LINQ reaches values, it throws error: "Conversion from string "Black" to type 'Integer' is not valid". I have read that if I want to obtain a value, then I gotta use conversion function.
Here's code (button's Click event):
Private Sub GetEnums(ByVal sender As Object, ByVal e As RoutedEventArgs)
lstEnums.Items.Clear()
Dim typeName = Type.GetType(txtEnum.Text)
Dim enums = From en In typeName.GetEnumNames
[code].....
How would I go about counting the number of times a given query occurs inside of a text file using LINQ?I need to search through the attached file and see how many justices were appointed by each president, and then create a new text file displaying the following:
presName, justiceCounter 'president name ordered by first name, number of justices appointed
I pretty much get how to do everything except for keeping an accurate counter within the LINQ query. However, I do feel confused about the order in which I should write this code, as in where I should keep my counter for how many justices a given president has appointed.
My output is displaying like this:
Abraham Lincoln,111
Abraham Lincoln,111
Abraham Lincoln,111
[code]....
I have following data in the arraylist..
HTML
ID Type Size
1 Car 1 1000
2 Car 2 1100
3 Car 3 1200
[Code]...
For a class project I am supposed to search through the attached file, and write to a new file the years between 1789 and 2009 that are not present in the fifth field. What is my best bet for determining what years are not present?
[Code]...
Should I make an array of integer between 1789 and 2009, then search for every year in the file, then set a flag to false if not found; is there a simpler way to accomplish this using LINQ?