How to: Assign an XML Schema Collection to an XML Data Type (Visual Database Tools)
Columns that use the xml data type can have the XML values validated against an XML schema collection. For more information, see Managing XML Schema Collections on the Server.
The schema collection must exist in the database before you modify the table. If you create a new schema while modifying the table definition, the schema collection list will not include the new collection.
To assign an XML Schema Collection to a column
In Table Designer, highlight the column with the xml data type.
In Column Properties, open the XML Type Specification node.
In (Schema Collection), select the schema collection you wish to use for this column.
If you need to create a new schema collection for this column, save the table and exit the Table Designer, create the schema collection, and then reopen the table definition.