Query Null Value In .net?
Feb 11, 2010
This seems like a pedestrian problem, but I just can't seem to find a solution. My problem is that I can't seem to find a way to search my datasourcefor a null value. Here's a simplified version of the problem: suppose we have a form with 3 textboxes and we wish to find a record on our datasource. if fields 1 and 2 have a value and field 3 is null, then how can I make a query using .net that searches for the values of the first 2 fields and a null value for the 3rd field? For example, suppose field 1 has a value of "ABC" and field 2 has a value of "DEF" and field 3 has a null value Now, how can I construct a query that searches "ABC" for field 1, "DEF" for field 2, and null for field 3?I'm using sqlce and below are some examples of what I've tried so far:
Dim Fld1 As New SqlServerCe.SqlCeParameter, Fld2 As New SqlServerCe.SqlCeParameter, Fld3 As New SqlServerCe.SqlCeParameter
Fld1.SqlDbType = SqlDbType.NVarChar:Fld2.SqlDbType = SqlDbType.NVarChar:Fld3.SqlDbType =
[code].....
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Nov 15, 2011
I'm querying a SQL DB and sometimes the result is Null, so I thought I would test this but my code results in an error "Data is Null. This method or property cannot be called on Null values."
Here is a snipet of my code:
For i = 5 To 6
cmd = New MySqlCommand(query2t & i, db)
rdr = cmd.ExecuteReader()
rdr.Read()
If Not IsDBNull(rdr.GetUInt32(0)) Then
[Code] ......
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Dec 22, 2009
I have a sql query which is returning null value below is the section the iID is null.Once debugger reaches this it goes to exception as its result is NULL. How to control debugger from going to the exception.
[Code]...
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Nov 12, 2011
From r In ReceiptLines
Where
r.RECEIPT.RECEIPTDATE >= _reportStartDate
And r.RECEIPT.RECEIPTDATE <= _reportEndDate
[Code].....
I am fetching all departments and their sales, average, count from the ReceiptLine, Receipt, ReceiptDiscount tables. The problem i am facing is, if i remove where discount > 0, I am getting null exception. But if I include that, then I only get sales that has discount. How would I write query that bring all sales less discount (if it has one).
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May 8, 2012
I have a select statement which was returning the required values but when I changed the OS date from English(US) to English(UK), it now returns null. I believe the problem is concerned with date since in the query am selecting values where the date from the database is the same as the date in a combobox but I don't know what else I can do. It almost looks like the dates in the combox and in the database are not the same and yet the date in the combobox is actually retrieved from the database and has been returning values fine until I changed the system date format.Here's my select command:
cmd4.CommandText = _
"SELECT sum(brought_qtty), recieved_qtty from brought_coffee, centre_weigh where brought_date=#" & _
dtComb.Text.Trim & "#" & _[code].......
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Feb 2, 2011
I'd like to take all suggestion either in C# or VB.NET.I have a DB diagram like the image below. I also include the database script here [URL]In the Students table, CountryId and RoomId column are allowed null. Because some records do not have info about room and country yet.Also, some students do not have essays.I'm doing a joint query with all tables. I want to select all students to project the result like this:Wanted query result.
Here's my current query that gives the result like the image below:
Dim db As New DBDataContext
Dim query = From st In db.Students _
Join c In db.Countries On c.Id Equals st.Id _
Join r In db.Rooms On r.Id Equals st.RoomId _
[code].....
current query result I got only one result back because I have (2) William NoMan record in every table. But I don't get anything about others, like (3) Sync Master who has everything but RoomId.What do I need to modify the query above so it will give me all students like in the wanted query image above?
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Feb 15, 2012
I m trying to filter a sql db with many filter criteria which inert the user in textboxes .. i ve tryed this query
[Code]...
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Jun 22, 2011
've got a function that takes two parameters (a delegate and an integer) and then creates a LINQ MethodCallExpression, which it uses to gets the results:
Public Delegate Function CompareTwoIntegerFunction(ByVal i1 As Integer, ByVal i2 As Integer) As Boolean
Public Function Test(ByVal pFunc As CompareTwoIntegerFunction, ByVal i1 As Integer, ByVal
[code].....
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Dec 15, 2011
I have a fairly simple piece of code:
Private _PurchaseDelivery as PurchaseDelivery
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As PurchaseDeliveryItem)
[Code]....
Which is inside a class which overrides a custom list base. The code is occassionaly throwing an unhandled exception, System.NullReferenceException, on this line when used in production:
If _PurchaseDelivery IsNot Nothing AndAlso _PurchaseDelivery.DefaultSKUBinID.HasValue Then
DeafultSKUBinID is declared as an Integer? (Nullable Int) in the PurchaseDelivery class. I cannot see what might be causing this error, why would this be returning an error?
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Jul 15, 2011
How to check whether a column is null i use the following code but I got this error "Input string was not in a correct format."
[Code]....
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Aug 12, 2009
When I put a break point to the last if clause in the sub ("If (backOrder < 0) Then", see below) it runs until the break point, if I put the break point further below, I get the following error:
Cannot insert the value NULL into column 'OrderID', table 'WHM.dbo.OrderDetails'; column does not allow nulls. INSERT fails. The statement has been terminated.
I've discovered first hand that it only happens when prodqty is bigger then qtyOnStock, thus executing the if clause.
The code:
Private Sub NCOSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NCOSubmit.Click
Dim sqlText As String = ""
[Code]....
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Aug 19, 2010
Here is the code:
Function getData(ByVal id As String)
Dim reader As SqlClient.SqlDataReader
Dim statement As String
[code].....
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Feb 29, 2012
When Creating a query using the sear Criteria Builder . I keep getting the error : "The schema returned by the new query differs from the base query" what does that mean and how do i avoid this problem in future
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Oct 20, 2011
I am trying to create a treeview in VB.net, the data has to be loaded from MSAccess 2010 database. When I try to run this program I get error : Argument Null Exception was unhandled, 'column' argument cannot be null and the program crashes. I have pasted the code as under:
Imports System.Data.OleDb
Public Class frmRating
Private Sub frmRating_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles
[code].....
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Jun 24, 2010
I have some code which gets child items for a menu via the GetChildren function which takes a list of menuData: Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
If menuData.Children IsNot Nothing Then
menuData.Children.AddRange(GetChildren(menuData))
End If
Next
If I check if menudata.children isnot nothing, it always is nothing because the GetChildren function is yet to run (providing the child items, which do exist). If I remove this check and just have this code:
Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
menuData.Children.AddRange(GetChildren(menuData))
Next
Then I am presented with a Object reference not set to an instance of an object error on menuData.Children.AddRange(GetChildren(menuData))
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Apr 28, 2010
I am connecting to an Access database and using a parameter query with the LIKE operator to return all rows that match query. The string to search for is taken from a Textbox
sql =
"Select * FROM Allview WHERE Info Like" &
"*" &
CStr(TextBox1.Text) &
"*"
The query does not return any data in vb, but when run from access with same string, there is data returned.The connection to the database is done correctly, as I am able to return data with various other queries.
Partial code :
Dim
con As
New OleDb.OleDbConnection[code]....
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Apr 7, 2012
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]
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Aug 27, 2010
The database:
"ID (Primary key)" | "Title"
0 | "title1"
[code].....
OK, before adding values to database, we should check if a row exists with this values :)TO do this, creating a Stored Procedure is a best way to deal with the database fastly.So... The problem now is, at the runtime, Miss OleDB throw this error:Microsoft Jet database engine cannot find the input table or query 'IF
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May 29, 2009
i should say hi experts :D . Help me with this pretty code :)
The database:
"ID (Primary key)" | "Title"
0 | "title1"
[code].....
OK, before adding values to database, we should check if a row exists with this values :)TO do this, creating a Stored Procedure is a best way to deal with the database fastly.So... The problem now is, at the runtime, Miss OleDB throw this error:Microsoft Jet database engine cannot find the input table or query 'IF
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Sep 14, 2010
I 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]....
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Oct 15, 2011
I created a RDCL in the designer. I would like the User to Determine what is shown in the Report. How can I change the query at runtime? (ex. changing the customer Name)
This is the query that I have in the properties:
SELECT [Date], Address, Customer, Orders
FROM Report_qry
WHERE (Customer= 'JohnDoe')
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Mar 11, 2010
how to take a query that returns a single row of data and load that data into textbox controls.I know about ExecuteScalar but it is only good for a single column of data from the query.
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Jul 11, 2010
I've got confused at the moment.I've got one database to developed for MLM (Multi level marketing) company.so, there's one Members database.. each member have unique ID called membercode.. and all members can members under them.. can make 2 members down to 1 member.. all members are added in same table named "tbMembers" and for each member there's a "parentID" where I add member's membercode under whome that member is?.. right?
Now what's the matter is .. I want a SQL Query which can go under and under.. like 'John Doe' having two members under him named 'Suzan' and 'Ellie' and 'Suzan' is also having 2 members under her.. and same for Ellie. and for example.. 'John Doe' having about 300 members in his down line? All members are making transactions.. like they purchase product and Invoices are being generated (invoices tables have 'memberID'). Now the query is how to generate query which can calculate John Doe's Downline's TurnOver from invoices table's 'totalAmount' field's SUM?
I'm using Asp.net 2.0 (VB.net) and use SQL Server 2005 Express.
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Oct 22, 2009
I have created a parameterized query in my tableadapter. Here is the SQL:
SELECT CalcinerID, Comments, CorrectiveActions, CrucibleOxideWt, CrucibleWeight, DCPressure, DCTemperature,
Date, DischargePressure, FeedPressure, FiredCrucibleOxideWt, GmSampleWt, LIMSNumber, LotNumber, MaterialType,
OperatorID, QualLabOperator, QualLabTimeStamp, RecordID, ToteBinNumber [code]....
When I use the Execute Query button in the Tableadapter Query Builder, the query works fine; I get all the rows I expect. However, when I run this in my code, the query behaves like an equality statement (i.e. Lotnumber = @Lotnumber) rather than a LIKE statement (Lotnumber LIKE '%' + @Lotnumber + '%').Here is the code that is not behaving correctly. Note that I have a textbox, LotSearchTextbox, where I enter the portion of the Lotnumber that I want to use as the filter. I also have a button, LotSearchButton:
Private Sub LotSearchButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LotSearchButton.Click
Try
Dim SomeNumber As Integer = Me.LotCalcinerO2TableAdapter.FillByLotNumber(Me.CalcinerDBDataSet.LotCalcinerO2,[code].....
why the query works in the Query Builder but not in the code?
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May 17, 2012
I have a data table that looks like this:
USERNAME ICOUNT IAVERAGE DATE_LOGGED
LAGX01 1245 1245 05-07-2012
LAGX02 2211 1422 05-07-2012
LAGX03 1698 1112 05-07-2012
LAGX04 4598 1555 05-07-2012
LAGX05 2589 3245 05-07-2012
LAGX06 3321 1155 05-07-2012
LAGX07 3698 3458 05-07-2012
LAGX08 2589 4587 05-07-2012
LAGX09 1598 1142 05-07-2012
LAGX10 3156 1987 05-07-2012
LAGX11 5547 2011 05-07-2012
LAGX12 9456 3459 05-07-2012
Now, I want to execute a sql query that will display the top 5 based on average, so i did this:
SELECT DISTINCT USERNAME,IAVERAGE FROM myTable WHERE IAVERAGE > 0 AND DATE_LOGGED='05-07-2012' ORDER BY IAVERAGE LIMIT 0,5 and the result is:
USERNAME ICOUNT IAVERAGE DATE_LOGGED
LAGX03 1698 1112 05-07-2012
LAGX09 1598 1142 05-07-2012
LAGX06 3321 1155 05-07-2012
LAGX01 1245 1245 05-07-2012
LAGX02 2211 1422 05-07-2012
Now, I want to numberize my query result, so it will look like this:
RANK USERNAME ICOUNT IAVERAGE DATE_LOGGED
1 LAGX03 1698 1112 05-07-2012
2 LAGX09 1598 1142 05-07-2012
3 LAGX06 3321 1155 05-07-2012
4 LAGX01 1245 1245 05-07-2012
5 LAGX02 2211 1422 05-07-2012
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Oct 31, 2011
I have 7 company Divisions that sit in an access database.I then use this list to populate two comboboxes in my windows form.However I get a syntax error in my SQL Query if the Division name is more than one word.For example in my access database I have two columns one is a status column and the other is a division column. If for example the Division is called 'Corporate' the status column is called 'Status Corporate' and the division column is called 'Corporate'.The SQL query works fine in this scenario.However if I have a Division that is more than one word, lets say 'Operations Division' I get an error in my SQL Query that says -
Quote: Syntax error (missing operator) in query expression 'Operations Division'.Here is my code
sqlNewTenderDetails = "SELECT " & Me.DivisionBox.SelectedValue & " From BidRefCodes Where " & "[Status " & Me.DivisionBox.SelectedValue & "='Active'"
daNewTenderDetails = New OleDb.OleDbDataAdapter(sqlNewTenderDetails, NewTenderDetailsTableCon)[code]....
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Nov 2, 2010
I've recently been trying to figure out a way to get parameterized queries to work and i think i'm almost there but seem to be getting an error when executing my query
Here's the code
[code]...
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Aug 24, 2009
I want to query an access database with variable data defined by the user. The "Search" criteria would be in a textbox. I made a query like
SELECT askID, Question
FROM chita
WHERE (askID LIKE 'Textbox10.text%')
and referring to this query as
Form1.ChitaTableAdapter.searchrec(Form1.ChitaDataSet1.chita)But id does not take the value of the textbox, instead it takes the Textbox10.text as a value. Is it possible to refer to it like this, or should I Linq?
[Code]...
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Apr 16, 2011
I was wandering is it possible to use a query within another query below is the code I am trying to use.
Public Function GetInventByComp(ByVal CompID As String) Using DC As New DataClassDataContext
'need to get company id's based off names? thats bad should be name from Id need to rethink this
Dim invent = (From C In DC.Inventors_Companies _
Where C.CompID = CompID _
Select C.InventorID).ToString
[Code]...
I was trying to us multiple values in a string like "1, 3, 5" but I can't seem to get that working either so I am trying to use just a single value now. Can anyone help me? "Yes I am new to this"
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Aug 28, 2011
I am using visual studio 2010 to create a form where you can edit,delete, or insert data from an accessdatabase. When I try to run the form in a web browser I get the error "Query input must contain at least one table or query." I believe that the problem lies with my code/syntax but I am unable to determine the cause of the problem.
<asp:AccessDataSource ID="AccessDataSource1" runat="server"
DataFile="~/App_Data/database.accdb" SelectCommand="SELECT * FROM [database]"
DeleteCommand="DELETE FROM [database] WHERE ([EmployeeID] = @EmployeeID)"
[Code].....
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