Working With Data In DataTables - Insert Into A New DataTable (dt2) Only Distinct "Type_And_ Model"?
Jun 22, 2011
I have a DataTable "dt1" that has thousands of rows.
Columns are:
- Type_And_Model
- Val_1
- Val_2
- Val_3
- Val_4
There are only about 30 different "Type_And_Model"-types.How can I insert into a new DataTable (dt2) only distinct "Type_And_ Model" types with the sum of their specific values and total appearance number?
dt1 - DataTable with thousands of rows
Type1 2 2 5 5
Type1 4 2 7 5
Type2 2 2 5 8
Type1 2 2 9 5
Type3 3 2 5 5
Type1 6 2 5 7
Type3 2 7 5 9
Type1 8 2 9 5
.....
INTO =>
dt2 -DataTable with disinct types and their sum values + appearance numbers.
Type1 22 10 35 27 5
Type2 2 2 5 8 1
Type3 5 9 10 14 2
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Jun 1, 2012
I'm having a hard time joining 2 datatables and have the joined datatable as result. First datatable (labels) holds data including a printerid. Second datatable (printers) holds printer references (id > unc). I would like to have as endresult (joined) a datatable with all data from the first datatable with the field (unc) of the second datatable. [Code]
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Jul 13, 2010
I am trying to distinct on multiple columns and get datarows from datatable. but getting error.
Dim query As IEnumerable(Of DataRow) =
(From row As DataRow In SourceTable.AsEnumerable() _
Select row.Field(Of String)("ColumnName1"),
[Code]....
I want another datatable with distinct row based on given columns from SourceTable.
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Oct 6, 2010
Currently we have a large DataTable (~152k rows) and are doing a for each over this to find a sub set of distinct entries (~124K rows). This is currently taking about 14 minutes to run which is just far too long.
As we are stuck in .NET 2.0 as our reporting won't work with VS 2008+ I can't use linq, though I don't know if this will be any faster in fairness.
Is there a better way to find the distinct lines (invoice numbers in this case) other than this for each loop?[code]....
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May 6, 2010
in a new project I thought I would try to integrate the new Entity Model Framework, but am having some issues/problems and would like to know if there is a solution or workaround that will let me insert a record into a table that has an identity property.At first I thougth it might simply recofnize the storedprocs that I have for insert/update/delte actions, and was a bit discapointed when generating the model ignored all my stored procs. So I thought wll heck maybe it just generates a nice insert method for me. Lets see.So I referenced my model and found that for the table (entity) there was an insert action (method) that had been generated, however what i found is that it explicitly added the primarly key field - which was based on an identity property and will not accept an explicit insert value.So I guess 2 questions
1. How do we work with identity properties
2. How can we take advantage of the performance and securtiy advantages that stored procs offer with SQL server?
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Oct 22, 2011
If I would connect to database I would run a query like this: "Select distinct Column1, column2 from tablename where somefield=somevalue order by column2". How can I run this query to a datatable? I know .select but that's not enough like dataset.datatable("name").select(filter,short). Still need distinct.
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Apr 6, 2012
I am using Microsoft Access database. Since Access Database Table cannot have more than 255 columns, I am using vertical database partition technique where I have splitted informations into 5 different tables. Each table has 100 columns, and first column is primary key. Now I need to read data from these five tables so that I can export it into Excel file.
[Code]...
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May 27, 2010
I have two datatables, which come from different sources. One is Sales, the other is Products. What I'd like to do is create a filtered version of Sales, in that in that it contains Sales which have a matching ProductID in Products.
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Dec 12, 2011
I have a datatable that contains 8 columns. To make this more presentable I have managed to pivot three of these columns. That will not do since I then loose 5 columns of information. To overcome this problem, I thought of just joining the two tables in vb.net.This seems more difficult than expected. LINQ are hard to learn compared to SQL. I have tried to pivot the query in SQL but am not able to.Here are the query:
"SELECT t1.Journal,t2.Kunde,t2.Kundenr,t2.Lokalitet,t2.Lokalitetnr,t2.Analyse,t2.Positive,t2.Totalt " & _
[code].....
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Dec 23, 2011
I am using strongly typed dataset and have many tables in that. The problem is now I want to filter data from
GetData()
function which has a query like
select * from table_name
How can I filter a particular table and distinct values from it. Also if I try to filter it return all column but rest have null values except the one I asked, so I cannot assign it as a datasource to a datagrid or combobox. How can I do this..
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Mar 14, 2012
I have a "result" which is DataTable and I like to get the x distinct values(City) and convert it back to DataTable how do I do this the code below gives me an error
Dim query = (From x In results.AsEnumerable()
Select (x.Field(Of String)("City"))).Distinct().CopyToDataTable()
so what I want is records of distinct cities I can get that but the problem I am having is converting it back to Datable.
Edited:I am using "where" in this statement and it does convert to Table(works fine) but not on "select"
Dim results = (From myRow In ds.Tables(1).AsEnumerable()
Where (myRow.Field(Of String)("xxxx") = xxxx)
Select myRow).Distinct().CopyToDataTable()
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Mar 13, 2012
I have a DataTable that has several hundred rows.I want to get a row count of distinct values in a particular column.For example, I have a DataTable of Product Orders, but I want to get the number of unique Customers.
I was using this code, but I can't rely on it because my binding source is filtered from time to time.If my binding source has filtered out all rows datatable.DefaultView returns 0 rows.
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Oct 19, 2010
I have a datatable which has been dynamically generated from FoxPro tables using a UNION Select statement. e.g.SELECT * FROM x UNION SELECT * FROM y UNION SELECT * FROM Z ORDER By v_alue1This produces a datatable with about 100 rows, each containing many fields, one of which is c_olor. From this datatable, I would like to select the distinct colors and then output in a dropdown.I have a public class Color which just has one property which I can then use as the DataTextField and DataValueField for the dropdownlist
Public Class Color
Private _c_olor As String
Public Property c_olor() As String
[code].....
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Jul 14, 2010
I am trying to get distinct rows based on multiple columns (attribute1_name, attribute2_name) and get datarows from datatable using Linq-to-Dataset.[code]How to do thin Linq-to-dataset?
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Sep 28, 2010
Is it possible to select distinct values from a DataTable?
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Feb 9, 2012
when I input data are not yet available. button does not work but when I enter existing data in the database, the button work for find existing records in the database and msgbox.appear this my coding. (i am using Microsoft Visual Basic 2008 express edition database mysql)
Imports MySql.Data.MySqlClient
Public Class Form2
Public conn As MySqlConnection[code].....
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Oct 10, 2011
I am trying to save data to database but I got a exception here is the code
Try 'connection is set
sqlcon = New SqlConnection("Data Source=MENUKA-PC\SQLEXPRESS;Initial Catalog=studentInformation; Integrated Security=True")
sqlcon.Open()
[code].....
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Oct 23, 2009
i fill a datatable in a typed dataset.. it has cities and states but I want to pull just distinct states and bind it to a control etc.. there is the filter, but i havent found a way to do distinct or group by. got to be a way without adding more datatables and filling them with data thats already there right?
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Oct 26, 2011
I want to track changes in an application. So I've made a copy of the main table in that application, and am accessing both tables in the application using two separate datasets.
My plan was to use the HasChanges method of the main DataSet to get changed rows and then insert those into the copy table. When I run the code I get an error:
A first chance exception of type 'System.InvalidCastException' occurred in MyApp.exe
Unable to cast object of type 'MainDataTable' to type 'MainAuditDataTable'.
Here's the code:
If Me.DataSet3.HasChanges Then
' 'look for each row that has changes, not new rows
' 'insert that row into the auditing table
[Code].....
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Sep 27, 2010
When I declare two datatables and fill them both from a datatable returned by a function in class, that when i filter the one it seems to filter the other aswell?
For example:
I declare the datatable and initiate my class:
Dim DatatableOne As New Datatable
Dim DatatableTwo As New Datatable
Dim MyClass As New MyClass
I then call the function that returns a datatable and apply it to datatable1 and 2 Then fill two DataGrids with the table:
DatatableOne = MyClass.GetTable()
DatatableTwo = MyClass.GetTable()
DatatableOne.DefaultView.RowFilter = "Name = 'Tom'"
[CODE]...
For some reason i don't understand but both grids end up with the filtered data?
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Jan 31, 2010
I'm working on making a game using VB, and part of the game involves being able to cast magic. What I did was put all the magic spells into a table in a database with the various properties I'll need at one point or another.The problem is that I need to only be able to select from a list of certain spells (Namely those your character is strong enough to be able to cast), and have it display the cost of the spell in a text box. My way of getting the right spells was as follows..first mak the structure of the table: [code] how can I use that usableSpells table I made as though it were in a database (IE making a textbox have something like "usableSpells.Spell_Cost" and making it display the relevant cost)? Trying to do it directly gives me "'Spell_Cost' is not a member of 'System.Data.DataTable'.,
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Mar 14, 2012
I am building a custom search control in VB.NET and came across a problem getting distinct records into my datagridview. I want to bring exact matches back first so I run 2 of the same query on the same table with a slight difference:
select ... like "code%"
select ... like "%code%"
I have a datatable that I need to get distinct records from; I am append records from a sql query to the end of the datatable so I cannot use a union in sql to return the dataset (I want to preserve the order which the rows are added) I have been using this which is working fine for 2 fields:
dt2 = dt.DefaultView.ToTable(True, "Code", "Name")
But when I have 3 (or more) fields I get duplicates ONLY for the row I am querying:
dt2 = dt.DefaultView.ToTable(True, "Code", "Name", "Initial")
select ... like "initial%"
select ... like "%intial%"
I am clearing the datagridview.source before rebuilding this. Is there a way to get the distinct rows this way or should I just build something myself to remove the duplicates from the second datatable before appending them to the new table?
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Mar 29, 2010
I created a DataSet using the DataSources wizard. I can display the rows of each Datatable one at a time. But in this case, I needed to add a new DataTable (newDT) using the Add New Table Adapter control(?) on the toolbox. newTable is derived by JOINing three different existing tables (or, dataTable) in my DataSet designer. The query works fine and returns all the data as expected. Trouble, if I try to display the rows of the newDT on textboxes, I get a NULLREFERENCE Exception.
[Code]...
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Mar 9, 2012
I have a datatable as shown in the figure. Let me explain my required based on this image. I have 7 rows of data. The rows 1 and 2 contains columns till UnitSqcNo same. I want only row 3 among the two. In general I want select all the rows with distinct model, unittype, unit and rest with greater CompId. ie the table should look like
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Nov 8, 2011
I load a list from a database like the example below. The class has more properties that the database table holds so when I load the list from the DB, there are Null values for certain properties of each item in the list. When I try List = List.Distinct.ToList, it never works (when null values are present).
[Code]...
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Mar 3, 2009
Visual Studio 2008VB.NETFramework 3.5Windows Application
I have a SQL database names TestSQLVB
In it a table called tblTest2, with a three fieldstest2id , int, pk, increment by 1field1, varchar(50)field2, varchar(50)
I have a dataset named Dataset2.xsd
A tableadapter named tblTest2TableAdapter
A insert query names InsertTest2 with fields @f1, @f2 and ExecuteMode = Scalar
When I run the following code per MSDN [URL] the database does not get updated.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim testds As New DataSet2TableAdapters.tbltest2TableAdaptertestds.InsertTest2("One", "Dog")
End Sub
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Jun 14, 2011
I have a sequence that reads the selected Excel-file and displays the first row of the columns in the Excel. (The first Excel row has the column names)
Dim cmd As OleDbCommand = New OleDbCommand("select * from [" & tableName & "$]", MyConnection)
Dim dr As System.Data.IDataReader
Dim dt As New System.Data.DataTable
dr = cmd.ExecuteReader
dt.Load(dr)
With the above code I can read the the first rows of the Excel table and choose the names of the columns I like to keep. (By populating the first row to my ComboBoxes)
So, at the moment my DataTable dt has all the table header names but on the first row. And as the header names it has F1, F2, F3, ... F13.
How can I make my new DataTable dt2 take the first row of dt and make it the column names row? How can I choose which columns do I want to transfer from dt to dt2 ???
I have tried the following (Doesn't work):
Dim dt2 As System.Data.DataTable
dt2 = dt.Copy.Columns("F1", "F2", "F3", "F4")
DataGridView1.DataSource = dt2
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Dec 22, 2011
I load a 47,000 line Text file into a Datagridview, not a problem at all.
I would like to get the Distinct values for Column1. I have been scratching my head on how to do this, I have not as of yet found an easy way to do this,
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Mar 29, 2012
fetching data from simulated model
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Feb 25, 2011
in the sense that MVC does not complain about my protected inner abstract Metadata class, and the model validation still works:
Partial Domain Object, generated by a tool:
Partial Public Class SampleDomainObject
Private _id As Integer
[code]....
I did this because I didn't want to have to implement actual properties with backing fields, getters, and setters in VB.NET for the Metadata class to keep the maintenance to a minimum (I'm on .NET 3.5, no auto-properties for me).What I'm worried about is that having a protected abstract inner class could be confusing to others using this domain object outside of MVC (my domain objects are part of a shared data access framework).
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