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How to Catch Duplicate Entry - Primary Key

Submitted by admin on Fri, 09/04/2009 - 14:43

in

Level: Beginner
Language: Visual Basic

5954 reads

This tutorial will guide you on how to determine if the primary key entered is already exist in the table. I created this tutorial in the hope to help newbie’s programmer solve this common problem.

Instead of displaying the default message cast by Visual Basic a message “Employee ID already exist. Please enter another Employee ID.” will appear.
For those who would like to see the source code without downloading the attachment here it is:

Private Sub CmdAdd_Click()
On Error GoTo err_CmdAdd_Click
 
    Dim cnData As New Connection
    Dim rst As New Recordset
 
    cnData.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\Data.mdb;Persist Security Info=False"
 
    With rst
        .CursorLocation = adUseClient
        .Open "SELECT * FROM Employees", cnData, adOpenStatic, adLockOptimistic
 
        .AddNew
 
        !EmployeeID = txtEmployeeID.Text
        !Firstname = txtFirstname.Text
        !Lastname = txtLastname.Text
 
        .Update
 
        MsgBox "Record added successfully...", vbInformation
    End With
 
exit_err_CmdAdd_Click:
    Exit Sub
 
err_CmdAdd_Click:
    If Err = -2147467259 Then
        MsgBox "Employee ID already exist. Please enter another Employee ID.", vbCritical
    Else
        MsgBox Err.Description, vbInformation
    End If
End Sub

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Primary Key.zip

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5954 reads

Hi Sir

Submitted by Anonymous on Sun, 08/22/2010 - 18:23.

Dear Sir,
I am a beginner, Can I get same Code (check "Data already exist" ) for VB.NET

Regards,
Sumesh. AV
Email: sumesh.av@gmail.com

reply

save the key returned when you create a record

Submitted by Anonymous on Sat, 05/01/2010 - 03:49.

Most databases (all of the major ones) will return in some variable the key of the record just created. The name of the variable used differs from one database to another, but they all return it in some form. So, when you create a record, save the returned key, then use that to find the record that you want to add data to.

reply

tnx

Submitted by Anonymous on Tue, 01/12/2010 - 00:27.

ayos to tol salamat ala ako masabi 1st time ko na pumonta d2 sa site na 2 at aUs dito
tnx ulit...this code is really useful to beginners like me......galing mo

reply

in Php Check Duplicate

Submitted by Anonymous on Fri, 11/13/2009 - 12:16.

How to do this in PHP?

if possible please help.

Best Regards,
Vilart

reply

re: in Php Check Duplicate

Submitted by admin on Fri, 11/13/2009 - 21:31.

The concept is still the same except PHP is using different approach when calling a recordset.

First you need to execute a query with the WHERE clause and check if the record exist.

reply

vb6 using DAO

Submitted by Anonymous on Fri, 09/18/2009 - 10:18.

i have a thesis and im programming charge invoice i'v got a problem in save button after i add the data in the header and then seek for the customer number to store the last CI number in the customer file i go for a check of NOMATCH? if it is not found then i go for clear all my fields but the problem is that the date is already in the database..
how can i trap this without duplicating the data or not to have a run time error.please help tnx..

im looking forward for your reply...

proud to be pinoy..

reply

HELP US we need a code for computation!!!!!!!!!!!!!

Submitted by Anonymous on Sat, 09/05/2009 - 22:47.

we are having a defense and our program really sucks we dont have yet code in computing the installment and cash basis alson the code on printing the statement of account plz help us thanks!!!!!!!!!!!!!1v//.+) u . . .

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Hi Sir

save the key returned when you create a record

tnx

in Php Check Duplicate

re: in Php Check Duplicate

vb6 using DAO

HELP US we need a code for computation!!!!!!!!!!!!!

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