Preventing Duplicates

[gtcoglan]

Hi,

I have a form and within that form there is two combo boxes and one text box. When one choses a value from one combo box, and then chooses a value for the other combo box and then enters the value into the textbox I don't want the user to be able to enter the same arrangement. That is I want to prevent duplicates on that combination. Also if they do this I want a Message Box to appear saying that that this combination already exists

I was thinking of using a multiple field index to prevent the duplicates, but I don't know if this is a wise thing to do. Can someone give me some help to see how I can prevent duplicates or offer another solution to prevent duplicates on the combination of the values.

Thanks
Greg

 

[andrew93]

Hi Greg

I'm not sure what you mean by 'multiple field index' but one way of preventing duplicate entries is in your table design - select multiple fields and click the 'key' symbol. This might be what you mean when you refer to a 'multiple field index' - I have also seen it referred to as a 'joint primary key' - no doubt there are many other names for this.

The fields combined must have a unique value, but each field individually can have repeating values. I'm not sure how well that method is supported on this forum but it is a technique I use frequently for exactly the reasons you posted. If I have described a 'multiple field index' correctly, I'm curious as to why don't you think it is wise thing to do.

Andrew

 

[DaveJHPT]

I'd recommend you set up a multi-field index (with no duplicates) over the three fields you have, but don't make that your primary key.

Dave