I am using VS 2008 and MySQL. Which one of the following methods is efficient or a proper one to check if record exists or not before making an attempt to insert.
1. HasRows Property.
2. Select Where Exists
3. Select Count(*)
Or if there is any other appropriate method ( which i am not aware of ) available to do it in vb.net ?
I have a small database. 2 main tables called CaseDetails and Checks.Each record in CaseDetails can have 3 checks recorded against it in the Checks table. But can only have one check of each type (check types 1, 2, 3).I have 3 linkbuttons which will take the user to the input form for each 'check'. If a 'check' already exists i want to hide the linkbutton that takes the user to that 'check type' input form (the 3 input forms have different fields).So what i need to do, is connect to the SQL database and see if a record exists for each 'check type' and hide the linkbutton to prevent users from entering another record with the same 'check type'?I have tried reading the reults into an array and examining that array, but havent been able to do so.
View 5 RepliesI have a tenant details form that has a field called TenantID, I also have a Lease table that also has a TenantID field, what I want to do is click the lease button, check to see if the lease already exists, if it does open the lease form to that record. If not then open the lease form to a New record so the user can enter all the information for that lease.
I am trying to use the below code but am having a little trouble understanding how it all works. What needs to be declared, what doesnt
HTML
Private Sub btnLease_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLease.Click
Dim fm2 As New LeaseDetails
[Code].....
I am importing alot of data from a text file into an access database with the code below. (From a Comma delimited text file) The problem is that I do not want to import duplicate records. I have the "IDNr" column in my access database set to "not allow duplicates" and need my code to check if there is already a record in the database before trying to import the data. Otherwise it will just give me an error or not import the rest of the data. I could do to make sure that there are no duplicates for the IDNr column?
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the next code is working but when I try to insert an existing record, it gives me an error and I want to add a msgbox to let people now that the username is already taken.Only the username cannot repeat on the database because it's the primary key.. the rest of the table rows can repeat.
Dim cn As New OleDbConnection
cn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Fabio\Desktop\Telemoveis\Telemoveis\Db_Tel.accdb"
[code].....
At the moment when a user logs into my system it checks to see if a job exists, if so the records are put into a datagridview. However, if there are no jobs in the database I get an error.
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i can't find any wrong, if record exists then updated the record but only can insert the new record.
cannot updated the record.why?
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i want to check if a file exists in the Application.StartupPath. I tried My.Computer.FileSystem.FileExists but that checks the whole computer doesn't it. ? How do i check if a file exists in a directory?
View 5 RepliesHow do I check if an HTML element exists? This element will only "show" on a certain event. ex: numbers in a non-number textbox or something. I tried
If WebBrowser1.Document.GetElementsByName("ElementName")
But that won't work, because the element "is in" the HTML, even though the page doesn't show it yet.
see if an object is already in a generic List(Of T) than the way I am currently doing it? The way I do it at the moment is like so:I have a method that I call each time I want to check to see if an object exists in the list (if it already exists I do not want to add it again) and the list to check is passed in to this method along with the item that should be added to it:
[Code]...
So as you can see this function just loops through the list that was passed in and if the DisplayName property of one of the items in the list is the same as the ProgramName argument that was passed in to the method as well then it returns True to indicate that this program is already in the list.I thought about using a Predicate with the List.Find method but cant see how I would get it to work because that predicate method will not have any way of referencing the list (its a method local list, not class level)
LDAP check dir exists when authentication is none Experts I am try to check if an LDAP path exists and the following code works fine if the AuthenticationType is not none. How do you check this if the LDAP does not use authentication?
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I am trying to check a record in database before inerting a new record here is my code but problem is when i enter a names first alphabet it imediatly populate massage. i want to check it after entering whole name
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
Try
Dim cnString As String = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" &
[CODE]...
I need to be able to have a loop which checks records in the database and if it matches up then do something. I need to check that zone = currentZone and if it does then to submit my update query.
View 7 RepliesWorking on an VB/ASP website in Visual Studio 2008. Getting the error "You cannot add or change a record because a related record is required in table 'abc'
It is true that table xyz (the target of the INSERT) is in a parent-child relationship with table abc. The PK in abc is a column RequestID_lng. The FK column in xyz is also named RequestID_lng
This is the only relationship these 2 tables are in.
I am trying to add a row in xyz with a value of 45 in the FK. There is already, previous to this action, a row in table abc with a value of 45 in the PK. So the parent already exists for this child.
I have used the watch window to copy my SQL code for the INSERT query that is being executed. I pasted that code into a new query in the Access DB and executed it without problem - it actually added the row that .Net should have.[code]...
I am having a ton of trouble trying to check if a record exists. I continue to get a data mismatch on my command.ExecuteScalar().
Code:
Protected Sub btnRegister_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnRegister.Click
[code].....
I have an default.aspx page that I'm trying to have redirect the user to a different page depending on whether or not their deviceId is stored in the SQL Server database. It should direct the user to the login.aspx if the record for the user is found or to the newdevice.aspx page if there was no record found. I want this to occur on Page_Load but have not been able to figure it out so far.
View 3 RepliesI'm updating an app for children I wrote in VB6 to VB2010. It uses a rather extensive MSAccess Database. It works perfectly but I need to update it to utilize better speech technology. I have read a lot about SQL and can't find how it is useful for anything accept business applications that add, delete or update records as long as you hard code in a name. I don't use datagrids and I never display a table. how to do a few things, I can figure the rest out.
In VB6, I had:
Option Explicit
Public db As Database
Public rs As Recordset
Public Reader As Recordset
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If you have been reading my posts I'm trying to learn this ADO.net code. So I have been reading and coding and I have a Question. How to I know in .net, if the record exists to make the decision to Add New Row or UpdateRow? Here is the code from the web I have been working with to better understand this, I could use some help on the decision making code needed to Update or New row.
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I was wondering if anyone could show me how to check if a tag exists?Here is the code that I am using to get the information from the xml.
Dim XmlFile As New XDocument
XmlFile = XDocument.Load(WorkingDirectory & "ToolsMediaInfoMediaInfo.xml")
Dim Manage = XmlFile...<track>
For Each XmlTag In Manage
If XmlTag.FirstAttribute.Value = "General" Then
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This is the standard way of checking if URL exists [code]....
return true; } catch (Exception ex) { return false; } But my problem is that we have to check it for around 100 URL's. It takes more then 2 minutes to check for all as it is trying to get response of all of them. Is there any way that we can check if URL exists without getting complete Response so that total response time is less.
In my code, I want to check if a referrer url exists and if the referrer url contains a specific sub string. I know how to check for the sub string:
If( InStr( Request.UrlReferrer.ToString(), "some sub string here" ) > 0 ) Then
But I don't know how to check if a referrer exists or not. No refer exists if the url is entered in manually in the address bar. So I tried this, but this does not work:
If (Not (Request.UrlReferrer.ToString() = "")) And (InStr(Request.UrlReferrer.ToString(), "some sub string here") > 0) Then
how do check if a referrer exists?
I have a windows service which fetches data from various datasources and build a XML file and send it to a webservice. For example first I will get customer details from Oracle Database and build the XML file and then the SQL Server database and build the customer details XML. I am planning to use the same function below to build the customer object irrespective of what the datasource is. But dr("age") column is not available in SQLserver datbase How can I check if a column exists or not.[code]
View 3 RepliesI am trying to check if a folder exist, it doesn't work if the folder name has a space or "_" or "-". .
here is an example of cases that don't work:
"Folder test"
"Folder_test""
"Folder-test"
I know how to make a new directory on an FTP server, but I wanted to know how I can check if a direcogtry exists, and if it exists display a message?
View 2 RepliesI am using Caspol.exe to install a custom Permission set and add Code Groups for my .Net 2.0 Windows Application.
I have created a Console Application that uses caspol.exe to add Permission Set and Code Groups. I first install the Permission Set and if I do not get an error, I continue to install the Code Groups
Now sometimes I need to add a new Code Group to the client machine, so I make the changes to the console app and it is executed on the client machine. If the client machine already has the Permission Set installed, it returns an error and stops the further processing.
So, I want to know if I can check whether a custom Permission Set is already added or not?
How would i just if a website exists, and, if so, launch a browser to open it. I am making a little tool for one of my freinds and it allow then to quickly launch websites. How would I check if that is a valid website to launch, so i don't get an error if it is not valid.[code]The error i want to stop is "Cannot start process because a file name has not been provided."So basically i want to make sure that the program can launch the URL so i don't get this error
View 3 RepliesI cant get the following code to check if my regestrykey exists can some one help. the idea is to check if it exists if so do nothing if not create it, along with its value...
the full key is HKEY_LOCAL_MACHINESOFTWAREVTSAdvanced Offset 2AdminAccess
> If Dir$("HKEY_LOCAL_MACHINESOFTWAREVTSAdvanced Offset 2Admin", vbDirectory) <> "" Then
[Code]....
I need to figure out if a registy key exists under the HKCU hive. If the key exists do this, if not then this.
View 6 RepliesI'm doing an application to manage a school of music, at the moment i'm working on registration (with MySQL DB).
Imports MySql.Data.MySqlClient
Public Class Admin_Reg
Dim server As String = "Server=localhost;Database=escola_musica;Uid=root;Pwd=;"
[Code].....
Now i want to verefy the table if the username exists or not. If it exists msgbox "Registration Complete", if not "Username already exists. Choose another one..."
I am trying to figure out how to check if a registry key exists. If it does, do nothing, if it doesn't, recreate it.I've found numerous resources on the subject, and have made progress, but one little thing is stoping me.[code]The problem is that this reports "Not Found", even though the key 'regkey' exists in the registry. Also, if I remove 'regkey' from the code, it reports "Found". So it does find the subdirectory in the registry.My question is, how do I check to see if the 'regkey' exists? I'm running Windows XP Pro SP2.
View 19 Replies