To decode the update_mask 0x00007C00 I wrote out the last 4 digits (‘7C00’, thats those with values plus those to the right) in binary 0111 1100 0000 0000 which (counting from the right) indicated columns 11, 12, 13, 14, and 15 had been updated.
simples 😉
UPDATE
Ok ok. Until I get round to convert the above logic into a big-dynamic-case-statement … here’s a script I adapted from here (http://dba.stackexchange.com/questions/35936/change-data-capture-and-the-update-mask-binary)
select (select cc.column_name + ', ' from cdc.capture_columns cc join cdc.change_tables ct on cc.[object_id] = ct.[object_id] where ct.capture_instance = 'dbo_MYTABLE' for xml path('')) as changedcolumns, * from cdc.dbo_MYTABLE_ct pd where __$start_lst = SOME_LSN_NUMBER