Monday, May 2, 2011

Lookup column in SharePoint 2010

Look up column in MOSS 2007:
If you want to display List data in a column in a SharePoint List, then we will use Look up column.
There are some disadvantages in MOSS 2007 look up column like: If you delete a value from the list, then any list referred to that element is going to be blank.

2nd is if you can only pick one column to show, If you want to show multiple column you cannot do that. Also if you want to display more information in the look up you cannot do that. So here it come SharePoint 2010 look up column.
SharePoint 2010 Look up column:

In SharePoint 2010 look up column you have the option to show multiple columns as below in the screen shot.

2nd major enhancement is the Relationship section. You can check the Enforce relationship behavior. Here you have two options as shown below:

Restrict Delete: This will restrict users from deleting an item in the column in the Look-up list, if the value is being used in some other lists.
Cascade Delete: If an Item\value in the column in the look-up list is deleted, then all those items referencing that value (as look-up value) in other lists will also be deleted.

Also there is an option to allow duplicate values or not.

So there will be one source list from which look up will get the values.