SharePoint: How to have a unique constraint in a list?

Question

In SQL its possible to have fields that cannot contain duplicate data.

How is this possible in SharePoint?

Lets say you have a list containing values like

ORANGES
APPLES 
PEARS

How do you ensure that the user cannot enter

ORANGES
APPLES 
PEARS
ORANGES

Thanks

Answer 1

This can't be done out of the box. But there are these community solutions:

• SPListConstraints (free but not open source)
• Unique Column Policy (open source, original solution by Scot Hillier)

Answer 2

Alex thanks for your answer man - don't take this the wrong way - but before you say - "t is a credit to the product's design"

Think of this scenario...

Lets say you had 1 million records....

And you needed to check for unique constraints....

IN SQL or MySQL or Oracle, this would happen in around 0.001ms. IN MOSS - this would take over 1 minute, I think possible 2-3 minutes (this is because you need to manually loop through all the items in the list using an SPListCollection).

So now consider if you wanted to insert 1000 more records into a table already containing 1 million records....

In SQL or MySQL or Oracle - this would take less than 1.5 seconds.... In MOSS lets do the maths:

1 item = 2-3 minutes x 1000 = 2000-3000 minutes... lets just make that 2500 minutes = 41hours....

You can't keep a straight face , and tell me SharePoint has good design...