Constraint Violation When Using Select Distinct?
Aug 6, 2009
I have a problem running a simple query: "select distinct payee from table". This query is set up in the dataset and is called GetAllPayee.My code goes something like:
Dim dtSources as new Datatable
dtSources =
Me.TblExpenseRecordsTableAdapter.GetAllPayee
Upon running I get the error:Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.The problem is, I haven't set ANY constraints on either the new datatable, or the dataset table (tblExpenseRecords). i.e. there is no primary key etc.
Can someone please help me out with this problem?I have no problems running the query through the wizard where I can view the results successfully.
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May 20, 2010
i am trying to write a code in which i need to perform a update but on primary keys how do i achieve it
i have written the following code: kindly look at it let me know where m wrong
[Code]...
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Apr 6, 2010
i am trying to write a code in which i need to perform a update but on primary keys how do i achieve iti have written the following code:
Protected Sub rgKMSLoc_UpdateCommand(ByVal source As Object, ByVal e As Telerik.Web.UI.GridCommandEventArgs) Handles rgKMSLoc.UpdateCommand
Try
KAYAReqConn.Open()
[code]....
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Jan 7, 2010
I have the following simple Sub to write a dataset back to an Oracle database
[code..]
Checking the logs today I noticed that for some executions I got an ORA-0001 (constraint violation) error. It seems that one of the fields in the oracle table being updated is marked as unique and my dataset contains one or more records that have the same value in that field.
How is this error handled? Does it just not add the violating records? Does it hit the invalid record and quit? Does it rollback?
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Jan 27, 2011
I have two function:
Public Sub AddData() Dim sSQL As String = "" Dim check As Boolean = Me.TestExistingRow("QUESTIONARIO1") If check = False Then sSQL = "INSERT INTO QUESTIONARIO1([USER]) VALUES ('" & Me.IdUser & "');" ExecuteNonQuery(Me.ConnString, CommandType.Text, sSQL) End If End Sub Public Function TestExistingRow(ByVal NameTable As String) As Boolean
[code]....
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Mar 18, 2010
I can't quite figure out why this Linq Statement isn't working as i would expect:
[Code]....
I would assume that this would create a new collection of anonymous types, that would be distinct. Instead it creates a collection the size of the "ThisParentCollection" with duplicate "MyAnonymousType" in it (duplicate id's).
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May 29, 2003
Is it possible to select distinct in the rowfilter method?
I have something like:
VB
'Create a data view so we can get each items name
Dim dvwItemNames As New DataView(dtlItems)
dvwItemNames.RowFilter() = "SELECT DISTINCT Name"
This gives me a syntax error exception. I tried just "Distinct Name" but this had the same result. "Name" is the column name. I would rather do it this way then looping through the entire table and putting the name in an array list or something.
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Aug 20, 2010
I have a single columned datatable inside a single tabled dataset.I just want to convert this dataset to distinct rows. Here is my code, it gives compile error '.' expected.
Dim query = _
From email In ds.Tables(0) _
Select email.Field<string>("Email").Distinct()
EDIT: I changed to (Of String) and it works... BUT NOW 'query' is an ienumerable collection of characters... not a datatable... so how do I convert back easily without manually doing a loop?
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Jan 4, 2012
I've a collection with the data like this.[code]...
how can select the distinct data using linq?
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Jun 5, 2010
I have set up a class to hold song information - artist, title. I then created another class that containg a BindingList(of clsSong). I use this binding list to create a data object that can be used to create an RDLC report. This all works. Now I am trying to remove duplicates from the binding list so they don't show up twice on the report. I can't figure out how to get a distinct list for my report. [code]...
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Jul 4, 2011
I used the following code to select unique values from the database [code]And it does not retrieve the unique values, it remains the same. But if I use only SELECT DISTINCT Author FROM tblBook it works fine.
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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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Oct 29, 2010
I have a form with a list box The code loops through a Tables' row and gives me only one of each of the catergories. If more than one of a perticular item exist it only displays one. i would like to use Select Distinct instead just because it would cut down on the time it would take to read the Rows items and still give me the same results I just am not sure how to write it.
[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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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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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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Oct 19, 2010
My particular example is fairly complex but I think the concept would apply equally to something like a logging system so I'll use that instead for ease of explanation. It's a ficticious example, please don't harp on or agonise over what is achitectually, programatically or morally wrong with the example itself
[Code]...
I don't want to 'cheat' and resort to a long-winded way of doing it when performance isn't critical here and I'm moderately confident it can be done in a single LINQ statement.
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Nov 8, 2009
I have an array with wild character at the end. I use the value in this array in Select statement. Some times the array has same values. I want only distinct values in the array before the select statment.
Code:
for i=0 to count
select * from tbl where item like ' " & itemname(i) & "'
next
I need distinct element in itemname array.
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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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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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Feb 6, 2011
Office 2010; Windows7; Visual Studio Basic 2008 (VB.Net)
[Code]...
The following strSQL string is not working as expected when run in VB.Net Interop to Access: (NOTE: The line-feeds " _" are used below are for reading only - are not in actual code line)
[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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Mar 20, 2010
I'm developing an app in VB.Net (Visual Studio Express 2008, on Windows Vista) that connects to an Access relational database. The database has 3 related tables (TextSections, LineItems, Cycles) that I'm loading into my dataset. I've set up two foreign key constraints and want all changes to cascade through the related records in the child tables. I cannot get the cascades to reflect through.
For example, when I delete the parent record, the children records remain (in the database - they are removed from the dataset). Also, when I modify the parent record (change the Description field for example), the change is not reflected in the dataset datatable that holds the children records - unless I go through and ReLoad all of the data from the database and re-Set the constraints. I have set the .AcceptChanges, .UpdateRule, and .DeleteRule to cascade, and have also set EnforceConstraints on the dataset. Why aren't the changes cascading through the children?
Below I've pasted (1) the Load Routines for my datatables TextSections (parent), LineItems (child), and Cycles (child of LineItems); (2) the method that creates the constraints in the dataset, and (3) The Save routine for TextSections.
Friend Sub LoadTSTable()
Dim key(1) As DataColumn
Dim newCol As New DataColumn
[code].....
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Oct 23, 2009
I'm experiencing some weird behavior when trying to modify some DataTable objects. Upon the second call to the subroutine, I get the following error when I to copy the source DataTable to a working set:
System.Data.ConstraintException was
caught Message="Column 'pk' is
constrained to be unique. Value
[code].....
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Jan 18, 2010
i just want to know if there is a way to implement constraint for parameters with a repeating pattern. For that i meant something like this
ParamArray pattern as Integer()
if i need an integer, and any amount of the "pattern" (the pattern here is one integer). so basically the pattern accepts 1 integer and multiples of 1 integer, meaning 2 integers, 3 integers so is there a way to upgrade this so we can have this pattern:
Integer, Boolean
and any valid combinations for this pattern will include
Integer, Boolean, Integer, Boolean
Integer, Boolean, Integer, Boolean, Integer, Boolean
etc, etc
currently the only way i can think of is to wrap Integer and Boolean as 1 object and apply pattern 1, but i was searching for a better alternative?
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Apr 18, 2009
I just watched a video from Beth Messi about setting up a primary key and foreign key on a table.
I created two tables, one called customer and the other one called orders CustomerID is the primary key to the customer table OrderID is the primary ket to the orders table and CustomerID is foreign key to the orders table
Beth Messi said that this would maintain the integrity of the tables and she also mentioned something about setting up a cascade delete so that when we delete a record in the customer table, the customer's order in order table will get deleted as well.
how I can set up the cascade delete, Meanwhile, I tried deleting a customer record in customer table - a customer with orders, and I got the following error when I clicked save.
The DELETE statement conflicted with the REFERENCE constraint "FK_Orders_Customer". The conflict occurred in database "C:DOCUMENTS AND SETTINGSLOUISLOCAL SETTINGSAPPLICATION DATATEMPORARY PROJECTSWBINDEBUGTEST.MDF", table "dbo.Orders", column 'CustomerID'. The statement has been terminated.
Shall I use try catch to warn the user that the record that I tried to delete has an order? They can't delete the customer unless the orders table's record is deleted first?
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Mar 28, 2009
I'm building an app that does calculations (in dollar amounts). I want to buildin a constraint that says the value entered into text box must be greater than 0. If the user does not follow this rule, I want them to get an error message.I have the calculations built and the error message, but not the constraint statement i.e. if users enter negative numbers the ouput is negative, which in the context of this app makes no sense. how a statement that would require the value entered into a text box to greater than a value.
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May 18, 2010
Im getting a constraint error when running the following code. there are four fields set as the primary key on the table: bid number, phase number, phase version, detail number.
It errors out saying that bidno, phaseno, phaseversion are the keys and unique. it does not mention the detail number, but it will error out as soon as i run the line dtDest = dsbid.phasedetail.copy....or, if i use the clone (as in the example below), it errors as soon as i add the row.
CODE:
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Aug 26, 2010
I have a datagridview in which the user can add new rows. The datasource is a datatable who has a unique-constraint for the column "Position". Thus, if the user enters a position already existing, an exception is thrown. To avoid the ugly standard error message, I simply handle the dataerror-event and set e.cancel = true. This works. But if the user presses escape, the row_validated-event is triggered. I use this event to format the rows containing new data by changing the font color to red. Here another exception is thrown (SystemOutOfRange-Exception) telling me that the index xxx has no value. How can I achieve row-formatting for new/modified entries without getting this error?
Here is my code:
''' <summary>
''' Catch exception and cancel illegal action.
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
[Code] .....
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