C# - Selecting Multiple Distinct Values In Database?
Sep 27, 2010
I have this online quiz that generates random questions, but the only problem is that it repeats the previous questions. I have limited questions (I have 10 questions in my table, but I have limited the number of questions to be 5. The output would only display 5 random questions) which I named as RequiredRecords.
question_id
1
3
4
[code].....
I have tried to visit this question, but it doesn't resolve my problem. Below is some of my code and SQL statements I used.
I figured out that there's nothing wrong with my query on creating random questions and I can display it with no duplication, but there's something wrong with my other codes that makes the program having a duplication.
Code Behind using VS2008 3.5
Partial Class Student_DetailView
Inherits System.Web.UI.Page
Shared TotalRecords As Integer
[code].....
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Dec 8, 2011
I f I have 1 combobox then my SQL query will be:
Dim objConnection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source = C:DB.mdb;Jet OLEDB:Database Password=Pass1;")
Dim objdataadapter As New OleDbDataAdapter("SELECT DISTINCT LOCATION FROM Table", objConnection)
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Sep 15, 2010
What iam trying to do is selecting rows on multiple column values. But the statement below doesn't preform like i thought it would...
Code:
Select Distinct Variable From TableName Where (ColumnA Like"%AAA%") And (ColumnA Like"%BBB%")
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Dec 14, 2011
I need to select distinct highways from a roads collection.
I suppose I could use LINQ for this.
I have (stub code)
Dim roads As List(Of Roads) = myRegion.Roads
Dim highways As New List(Of Highway)
For Each road In roads
[Code]....
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Oct 24, 2011
I have a DataTable with about 64 columns, including "UserAnswer", "CorrectAnswer", and "QID_Lookup". I am building a LINQ that will select all the rows that have a correct answer (user answer matches correct answer), but I only want to select rows that have distinct "QID_Lookup".
[Code]...
The problem is that the result set includes duplicate QID_Lookup values. How can I include only distinct QID_Lookup values? keep in mind that there are 64 columns, so if I can avoid it, I wouldn't want to list each column individually for selection.
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Aug 9, 2010
I am trying to get distinct values in column 2 of a DGV using the following LINQ query:
Dim AllocatedRoomTypes = From r In Me.AllocatedDGV.Columns.Cast(Of DataGridViewCell)() Select r.ColumnIndex = 2 Distinct
but I get the following error:
Unable to cast object of type 'System.Windows.Forms.DataGridViewTextBoxColumn' to type 'System.Windows.Forms.DataGridViewCell'
I understand that the problems lies with the Cast, but I do not know how to correct it.
What I am trying to acheive is this:
Value is Column 2 of DGV
Double
Double
Single
Twin
[Code]....
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Oct 25, 2011
I have a three column table which lists every person, every event they may have attended, and what percentage of the time they were there. I would really like to display this on one page with the person names on the side and the event names across the top.
Here' an example of what I have:
NAME EVENT %ATTENDANCE
Smith Rock Climbing 50
Allen Rock Climbing 78
[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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Feb 15, 2012
I have a database which need to be assigned into array arr()(), e.g.
arr(0)(0) = aa arr(1)(0) = ab arr(2)(0) = aa
arr(0)(1) = bb arr(1)(1) = ba arr(2)(1) = ba
arr(0)(2) = cc arr(1)(2) = cc arr(2)(2) = cc
I need to find distinct / unique value in each arr(k)(0), arr(k)(1), arr(k)(2); where k=0..2. Then i need to insert the result into array cat as follows:
cat(0)(0) = {aa} cat(0)(1) = {ab}
cat(1)(0) = {bb} cat(1)(1) = {ba}
cat(2)(0) = {cc}
I've tried code below but it doesn't work. The assigning process into array arr()() from DB is OK. Problem only come up if I try to find the distinct value (If Not (cat(j).Contains(ds.Tables(0).Rows(i).Item(j))) ... End If).
For i = 0 To 2
list(i) = New Integer(3) {}
For j = 0 To 2
[Code].....
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Mar 10, 2012
I have a List(Of Hardware) - the List is called HWModels
Class Hardware has the following Properties:
ModelName
Status
CPUStatus
MemoryStatus
DiskStatus
The List is populated by reading a CSV file, once it's populated, I want to return the distinct records based on the ModelName
I've attempted by doing it as follows:
(From a In HWModels Select a.ModelName).Distinct
But this isn't right because I end up with a list of only the ModelName's and nothing else.
How do I get the Distinct function to return all of the other class members within the list?
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Mar 9, 2011
Like "SELECT DISTINCT(Col)" in sql query, how do we perform this in datagridview?[code]...
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Mar 28, 2012
I'm pretty new in Linq and the first problem I've is to select the Distinct values from a ObservableCollection( Of T)
I've tried with[code]...
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Apr 18, 2012
Im having trouble getting the sum of a "Status Column" It is unbound. It has 2 Items "Active and Inactive" I would like to have lblInact.Text to show the total of Inactives of that column.
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May 24, 2011
I am trying to do this:
Dim viewdata2 As DataView = fxts.fxtsdata.Tables("clients").DefaultView
Dim viewsorted2 As DataTable = viewdata2.ToTable("clients", True, "Surname", "Name")
[Code]....
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Jul 2, 2011
Supposing the referenced List below contains 2 elements:
Dim Countries = From c In List _
Select New With { .Country = c.Country, .CountryID = c.CountryID }
The code above returns
.Country=Spain .CountryID = 1
.Country=Spain .CountryID = 1
How can I get the distinct values? The Countries query should contain only
.Country=Spain .CountryID = 1
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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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Dec 27, 2011
I have a combox and a datagridview on a form, the combox filters the datagridview but doesnt have Distinct values. I found this on one of your post. I have a Products DB Table with ProductID, Series, Description and UnitPrice, I am trying to filter the the datagrid using the column Series with the combobox but i get multiple values of the same thing in the combobox, where i would like to make it Distinct.[code]
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Sep 28, 2010
Is it possible to select distinct values from a DataTable?
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Jan 31, 2011
MY TABLE
sample comment1
sample comment2
[CODE]...
if sample column value is the same, i want all comments value to be concatenated
do while dr.read
listbox1.items.add(dr.getstring(0))
[CODE]...
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Mar 24, 2012
I have a Table:
[Code]...
I'm trying by LINQ-query (VB.NET) to return a count for distinct value of Objects, Stuffs and Colours for every Room:
[Code]...
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Aug 9, 2010
I have the following table structure. I want to select distinct CustomerId and CustomerName, TotalCost.[code]
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Apr 2, 2010
I'm using LINQ to SQL to select some columns from one table. I want to get rid of the duplicate result also.
Dim customer = (From cus In db.Customers Select cus.CustomerId, cus.CustomerName).Distinct
Result:
1 David
2 James
1 David
3 Smith
2 James
5 Joe
Wanted result:
1 David
2 James
3 Smith
5 Joe
Can anyone show me how to get the wanted result?
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Feb 15, 2012
I stuck to a place,where I have to Delete Values from Multiple Tables in the database
[code]...
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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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Jul 11, 2011
I have an EnumerableRowCollection that looks like the following:
VendorCode | GroupType | Variance
01165 G .16
01165 G .16
01165 CH .16
01165 CH .18
07754 G .25
07754 G .25
07754 G .39
Essentially, this is a massive list of vendor codes, their groups, and price variances. I need to compose a query that will create a distinct list vendor codes and group types. The catch, however, is that I need to evaluate all of the variances associated with that particular VendorCode/GroupType to see if they are all the same - it they are not, I need to return some way of signifying that the group has a "custom" variance, otherwise it needs to return the value (ie: if they are all .16, then return .16, if there are multiple values, return "custom")
The result would look like this, based off of the list I showed above.
VendorCode | GroupType | Variance
01165 G .16
01165 CH custom
07754 G custom
I have no trouble getting a distinct list of VendorCode/GroupType - this is what I have so far:
Dim distinctList = From q In query Select q.VendorCode, q.GroupType, (evaluated q.Variance here?) Distinct
(where "query" is an EnumerableRowCollection(Of (anonymous type)))
I'm at a loss, though, on how to evaluate the variance property to get the result that I need?
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Apr 16, 2010
basically i'm trying to reproduce the following mssql query as LINQ
SELECT DISTINCT [TABLENAME], [COLUMNNAME] FROM [DATATABLE]
the closest i've got is
Dim query = (From row As DataRow In ds.Tables("DATATABLE").Rows _
Select row("COLUMNNAME") ,row("TABLENAME").Distinct
when i do the above i get the error
Range variable name can be inferred only from a simple or qualified name with no arguments.
i was sort of expecting it to return a collection that i could then iterate through and perform actions for each entry. maybe a datarow collection?
As a complete LINQ newb, i'm not sure what i'm missing.
i've tried variations on
Select new with { row("COLUMNNAME") ,row("TABLENAME")}
and get:
Anonymous type member name can be inferred only from a simple or qualified name with no arguments.
to get around this i've tried
Dim query = From r In ds.Tables("DATATABLE").AsEnumerable _
Select New String(1) {r("TABLENAME"), r("COLUMNNAME")} Distinct
however it doesn't seem to be doing the distinct thing properly.
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Dec 29, 2011
I have three dropdownlist which values are to be inserted in one particular field in the database. But i am new to ASP.
This are my following codes:
Dim strConn = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
Dim myConn As New SqlConnection(strConn)
[code].....
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Jun 18, 2009
I have to compare an item value in two tables. these two tables are on different database(same server).
I have succesfully generated sql query to return both table values.
the query runs in sql server without any problem and gives the results.
The same query i used in vb.net doesnt gives any result ...
It is resulting with no rows.
Does the connection to multiple databases wont work from vb.net.
The following classes are used to get the result ...
SqlConnection
SqlCommand
SqlDataAdapter
SqlDataAdapter is showing with no records returned. The same query returns the results in sql server query window...
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