Parse Value From Database Datareader And Handle Possible NULL Value?
Feb 16, 2011
I have run into this problem a few times and have never come up with a good answer. I figure others must have dealt with this already.I have a datareader returned from the database and I want to use the values therein however values may or may not contain NULL. I would like to have a unction that takes in the value from the datareader and returns the value if it is not NULL and blank space if it is NULL.The problem I have is that the data-type of the variable I am testing is variable. It can be a String, and Integer or a DateTime. Can anyone suggest a simple way to test the value and then return the original value (as same data-type if possible) or something else if it is NULL
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Apr 18, 2011
I am reading dates from a table in a database to display in a DataGridView column that is formatted as a date. The problem is that when the value is null in the database my program errors out because it cant convert the value to a date. How do you guys handle this? *Edit: If I set the value of my date variable to "Nothing" it displays as "1/1/0001" in my DataGridView, and I would like the cell to be empty for the null dates.
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Jun 30, 2011
im using this bit of code to recieve data from a database. problem is if one off the values in the databass is null it kicks up an error how can i handle this so in the event of a null value it gives a "" string value
[Code]...
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May 18, 2010
What i want to do is to read a value either null or not null from my oracle database using DataReader and store in a textbox. But i have an error.InvalidOperationExcepionHow can i avoid this error.Or is it possible to catch the exception to ignore null values read by the datareader?If the option is to catch the exception how may i do it?
Dim Dr1 As OleDb.OleDbDataReader = Cmd3.ExecuteReader
Dr1.Read()
lect_name = Dr1.GetValue(1).ToString
[code].....
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May 17, 2012
im getting error when im trying to view a report from my vb2010. value cannot be null. parameter name: dataReader the following is the screenshot for my error and the codes:
[Code]...
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Jan 19, 2009
I read stuff from a SQL DB (database) using a data set. Some of the columns in the DB may contain NULL. I want to go through the table in the dataset and print, or use in some other way, the data. But when I try to use a certain data that corresponds to a NULL in the DB my program crashes.How can I detect - in the dataset - that it has no value and that I shouldn't try to use it?
Private Sub Get�rendenLista(ByVal e As System.EventArgs)
'----------------------------------------------------------------------
' This function fetches a list of �rende from the table �rende
'----------------------------------------------------------------------
Dim cno As New SqlConnection
[code]....
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May 24, 2011
I have some MS SQL field with NULL value. when i am trying to use below in VB.NET code no result comming...
1- dim sqlq as string = "Select * from table where name3 = null and address3 = null"
2- dim sqlq as string = "Select * from table where name3 = '' and address3 = '' "
But if same query # 1 i run direct SQL Query browser it works well.
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May 24, 2009
I've got a subquery that returns the most recent value from a child table. In some cases the subquery returns nothing. The query below fails at runtime because the inferred type of MemberPrice is decimal and is not nullable. [code]...
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Apr 26, 2011
What are NULL values? Sometimes when I try to assign a query to variable, I get error saying:
Type-Cast-Error. txtMiddleName.Text = Reader.GetString(2)
How can I put it that if the value of the Middle is nothing then txtMiddleName.Text = "". Working on VS 2010 (VB.net) EDIT 1: This is the error Message I get (Line 364 is the above mentioned code)
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Jul 17, 2011
On a ASP.net form, I need to add a textbox to update a date field in MS SQL server via stored procedure. I want to verify user input cant figure out the correct syntax to do so (please see below)
If d.Text <> "" Then
cmd.Parameters.Add("@date", SqlDbType.DateTime)
cmd.Parameters("@date").Value = Date.Parse(d.Text)
[Code].....
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Mar 30, 2011
I need to round and print a price like below, but this does not handle null values.How can I handle null values on one line of code? DBRSet is an SQLDataReader and the price is money
<%= Math.Round(DBRSet("price"))%>
I have about 200 .aspx pages of this so I could also use some tips on how to change these in an easy way? Can I do a search and replace with a reg-exp or something like that?
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Jun 11, 2009
In a WinForms app (VS2008 / .Net Framework 3.5) I bind data from SQL Server to controls. If there's a null value e.g. an employee has no middle name (allowed by business rules), when I browse that record at runtime an exception is thrown. So I code: If Not (row("middle_name") Is DbNull.Value then txtMiddleName.DataBindings.Add(New Binding("Text", row, "middle_name)). Say someone adds a middle name to this record, because the control had no databindings the dataset.HasChanges property is false and update stored proc doesn't run. I guess I could handle this like this: If txtMiddleName.Databindings.Count = 0 AndAlso txtMiddleName.Text <> "" Then row("middle_name") = txtMiddleName.Text. I guess I would have to do something similar to handle a value changing from not null to null.
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Apr 22, 2011
I am using KeyPressEventArgs to restrict several text boxes to numeric entries only. Rather than repeat the code, I thought I would make a "RestrictToNumeric" subroutine and call it from each "KeyPress" event. Like So:
Private Sub txt1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txt1.KeyPress
RestrictToNumeric()
End Sub
[code].....
The problem I am encountering is that the variable 'e' is used before it has been assigned a value, causing a null reference at runtime.
So I tried to add Dim e As System.Windows.Forms.KeyPressEventArgs As?to the RestrictToNumeric sub.I cannot figure out what I need to "Dim" it as...
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Feb 20, 2012
I have an SQL statement like:
SELECT FNAME, LNAME, CITY from EMPLOYEE
How do I create a multi-dimensional array from a datareader which should store values like:
John, Doe, LA
Mike, Johnson, PASADENA
Freddy, Kruger, Long Beach
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Aug 27, 2009
I have an RDLC report that I am rendering directly to the Response Stream as PDF (rather than using the ReportViewer). In the code that renders the report, it's DataSource is bound to a List(Of ClassA) objects defined in a custom assembly. This seems to work for the most part. My problem is that I can't seem to handle the situation where a nested object is null. For example, given ClassA and ClassB (the nested object) defined as follows:
Public Class ClassA
Public Id As Integer
Public Name As String
[Code]....
the report displays "#Error" if TheNestedObject is null. If TheNestedObject is not null, it correctly displays the Name.
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Feb 2, 2010
Im struggling to display the content of my database. I'd like to create a submenu (subpages within pages) to use in my CMS.
Here is my menu so far, as you can see the pagetitles are repeated for each subtitle. I only want one pagetitle to appear for each submenu.
About Us
Your Services
Equality and Diversity Team at SCHS
subpage title 1
[Code].....
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Feb 18, 2009
how to find out the total number of rows in a database through datareader
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Jan 4, 2011
I am trying to populate a listbox from an access database. It is a scheduling database. First my users pick a room they would like to add an event to, then a date. after the date is selected, id like the listbox to populate with meeting titles corresponding to the date they selected. The code so far looks like this:
[Code]...
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Jul 6, 2009
I'm building application that will heavily use database (about 25k query's in few hours) , what is the best way to go:
A) use datareader and open new connection to the database on every client query.
B) load all the needed tables into dataset once the program loaded and use that dataset for the query's?
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Apr 27, 2011
i have a form with one combobox and textbox now on other hand i have a sql database named balance with two column one as customername and and another as obbalance now i had binded all the customer name to the combobox now what i have to do is wen user selects a customername from the combobox the textbox should show the obbalance of the selected?
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Aug 17, 2009
I have a problem with my project. here is the problem:
My code for login is as follows:
dim conn as SqlConnection = New SqlConnection("Data Source.................)
dim cmd as SqlCommand = New SqlCommand("Loguser",conn)
cmd.CammandType = CommandType.StoredProcedure
[CODE]...
Now the error i get is that "there is a datareader associate with this connection that need to be closed"
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Oct 15, 2009
Ive created one database Sql Server Compact Edition 2005, with one table ("Cliente") I know that I can created my database good, but i have a problem saving information since three textbox, in my table(With columns "Nombre" "Apellido" "Cliente". In my form there is a button save ("Guardar"). When I do click in my button appear the next message : "The column cannot contain null values. [ Column name = Nombre,Table name = Cliente ] " and happen the same with apellido and Id_Cliente. And this happen becouse my code cant save the information....
This is the code
Option Explicit On
Option Strict On
Imports System
Imports System.IO
Imports System.Data
[CODE]...
And the code for my button is:
Private Sub cmdguardar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdguardar.Click
Dim myconnection As SqlCeConnection
Dim mycommand As SqlCeCommand
[CODE]...
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Dec 19, 2011
What i have now is a listbox which databinding to database,everytime i click the item on listbox, all related information will display on textbox.[code]...
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Apr 2, 2009
I'm writing a program that needs to parse data from a SQLite Database, I have the reference DLL but I do not know the proper syntax for the actual parsing of the file. The reference I have is located at [URL]..I don't really see any code that would need to be given seeing as the code for that class is currently something link:
Imports System.data.SQLite
public class SQLite
public sub Retrieve_Data
end sub
public sub Connect2SQLite
end sub
end class
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Nov 15, 2011
I have an email account that receives various requests to get free materials, for different items. These emails will usually contain name, item, quantity of item, address, state, zip. What makes it difficult is that all the emails are different, unstructured, and the data is usually buried in the emails, i.e. a forwarded email.I want a way to get all the information and parse it into a ms sql database.I know there are products that would work really well like url... but at work we can't afford this.I was thinking of creating a webservice that would input mail data posted from a third party site like cloudmail.com into a secondary website and then maybe creating a ruby script that would crawl the messages and extract addresses, etc. Anyone know of a good, simple alternative, a custom script in ruby, php, vb.net or possibly an open source solution?
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Jun 3, 2011
I have an email account that receives various requests to get free materials, for different items. These emails will usually contain name, item, quantity of item, address, state, zip.What makes it difficult is that all the emails are different, unstructured, and the data is usually buried in the emails, i.e. a forwarded email
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May 22, 2010
I have a directory full of .txt comma delimited files arranged as shown below. What I want to do is to import each of these into a SQL or SQLite database, appending each one below the last. (1 table)... I am open to C# or VB scripting and just not sure how to accomplish this. I want to only extract and import the data starting BELOW the 'Feat. Type,Feat. Name, etc' line.
These are stored in a mynetworkdirectorystats folder on my network drive. Ideally I will be able to add functionality that will make the software/script know not to re-add the file to the database once it has already done so as well.
[Code]...
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Mar 29, 2010
I need to parse a file name and compare to names in a data base. The file name has an underscore "_" as the delimiter. I need everything before the underscore.
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Jan 27, 2010
I have several installations of my Linq-to-Sql app running in the field. Now I've created a new version, which adds a new column to a certain table. I've added this column in the dbml file. But when updating the installation, I want to preserve the existing database. How to handle this? Linq-to-SQL doesn't seem to like this inconsistency.Is there an easy way to update the existing database using my new dbml file?
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Jun 8, 2012
I just want to parse simple expressions like IIF(FVAL(PFC) = TRUE, (IIF((ORGVAL(BAS, "2012/12/31") + ORGVAL(DA)) < 6500, (FVAL(BAS) + FVAL(DA)) * 12%, 780)), 0)`After parsing this I should be able to know what functions contains what parameters.
[Code]...
I'm stuck with .Net Framework 2.0, so no Linq or lambda expression goodies for me. Also I want to include the code in my custom library and not just reference it. Can anyone point me to some good library or code.
I just need to parse and not evaluate the expression and find what tokens are in use. After finding the tokens I need to change the expression string before parsing, like if the function ORGVAL is used then the parameter passed has has to be prefixed by an underscore. Like ORGVAL(BAS) will transform to ORGVAL(_BAS). Some functions can have tow parameters like ORGVAL(BAS, "2012/12/31") and this will transform to ORGVAL(_BAS, "2012/12/31")
NOTE: IF THERE ARE OTHER WAYS OF DOING IT PLEASE LET ME KNOW. I WOULD LOVE TO AVOID A PARSER AND LEXER.
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