I'm using that method (creating a unique index) for already existing tables. I mean without changing the original table.

If you able to change / redesign your table you can add a unique index on multiple fields. So inserting duplicate records gives a warning like 'Duplicate key was ignored', but no error.

For example:

CREATE TABLE phonebook (

[phonenumber] [varchar] (30),

[firstname] [varchar] (30),

[lastname] [varchar] (30),

[company] [varchar] (100)

)

CREATE UNIQUE INDEX IX_Unique ON phonebook (firstname, lastname) WITH IGNORE_DUP_KEY

But do not forget that, ADO will take 'Duplicate key was ignored' warning as an error!

So you should take care of this in your application.

A VB6 example;

Const cnstError_DuplicateKeyWasIgnored As Long = 3604

'...

On Error GoTo ADO_ERROR

Call oCON.Execute(strAnInsertSql)

On Error GoTo E 'Normal error handler

'...

ADO_ERROR:

If oCON.Errors(0).NativeError = cnstError_DuplicateKeyWasIgnored Then

'Duplicate Key Was Ignored errors should be ignored

Resume Next

End If