Declare TablesAndFields cursor for
SELECT objects.name as Tablename, columns.name as columnname
FROM
    dbo.sysobjects as objects
left join dbo.syscolumns as columns
on objects.id = columns.id
where objects.xtype = 'U'
and columns.xtype =  61 

open TablesAndFields

Declare @TableName as varchar( 100 )
Declare @ColumnName as varchar( 100 )

FETCH NEXT FROM TablesAndFields
    into @TableName, @ColumnName

WHILE @@FETCH_STATUS =  0 
BEGIN
    Exec ('update ' + @TableName + '
    set ' + @ColumnName + ' = dateAdd(year,-2000,'+@ColumnName+')
    where ' + @ColumnName + ' > ''3999-12-31 23:59:59''')

   -- This is executed as long as the previous fetch succeeds.
   FETCH NEXT FROM TablesAndFields
    into @TableName, @ColumnName
END

close TablesAndFields
deallocate TablesAndFields
update dbo._YearOffset set Offset= 0