How to Catch Duplicate Entry - Primary Key

Submitted by admin on Friday, September 4, 2009 - 14:43.

Language

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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Comments

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

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 . . .

You did't not specify the languge

******************code on printing the statement of account************ If rsc.State > 0 Then rsc.Close rsc.Open "Select * from TblCash where paidday ='" & CMBsalesday.Text & "' and paidmonth='" & CMBsalesmonth.Text & "' and paidyear='" & CMBsalesyear & "'", xec, 1, 3 Set CasherReport.DataSource = rsc CasherReport.Sections(2).Controls("Label1").Caption = "Date:" + " " + CMBsalesday.Text + " " + CMBsalesmonth.Text + " " + CMBsalesyear.Text + " " + "Income" CasherReport.Show

vb6 using DAO

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..

in Php Check Duplicate

How to do this in PHP? if possible please help. Best Regards, Vilart

re: in Php Check Duplicate

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.

same query ""check Duplicate

same query ""check Duplicate reocrd" How to do this in PHP? if possible please help. I wan source code Regards Lubna

tnx

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

save the key returned when you create a record

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.