🦆 rubber ducking __$update_mask & __$operation for SQL Server CDC

cdc-__$update_mask-rubber-ducking.sql

/*
https://learn.microsoft.com/en-us/sql/relational-databases/system-tables/cdc-capture-instance-ct-transact-sql

wanted to check that for ins/del ops (2 & 1 respectively) that the full update bitmask always applies

it does:
- 0x0f bitmask on 4 cols
- 0x7f bitmask on 7 cols
- 0xFF bitmask on 8 cols

*/
go
/*
use CdcTest
go
exec sys.sp_cdc_disable_db
go
*/
use [master]
go
drop database if exists CdcTest;
go
create database CdcTest;
go
use CdcTest
go
exec sp_changedbowner 'sa'
go
exec sys.sp_cdc_enable_db;
go
create table dbo.foo (
    id int not null primary key,
    a char(1),
    b char(1),
    c char(1),
    d char(1),
    e char(1),
    f char(1),
    g char(1)
);
go
insert dbo.foo 
    (id,a,b,c) 
values 
    (1,'a','b','c'),
    (2,'e','f','g'),
    (3,'h','i','j');
go
select * 
from dbo.foo;
go
-- https://learn.microsoft.com/en-us/sql/relational-databases/track-changes/enable-and-disable-change-data-capture-sql-server
-- https://learn.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sys-sp-cdc-enable-table-transact-sql
exec sp_cdc_enable_table
    @source_schema = N'dbo',
    @source_name   = N'foo',
    @role_name     = null,
    @supports_net_changes = 1;
go
/*
Update mask evaluation will be disabled in net_changes_function because the CLR configuration option is disabled.
SQLServerAgent is not currently running so it cannot be notified of this action.
SQLServerAgent is not currently running so it cannot be notified of this action.
SQLServerAgent is not currently running so it cannot be notified of this action.
SQLServerAgent is not currently running so it cannot be notified of this action.
*/
go
-- start SQL Agent, enable CLR, & restart demo
exec sp_configure 'clr enabled', 1;  
reconfigure;
go
/* -- success from sp_cdc_enable_table
Job 'cdc.CdcTest_capture' started successfully.
Job 'cdc.CdcTest_cleanup' started successfully.
*/
go
select * 
from cdc.dbo_foo_CT
-- empty
go
update dbo.foo 
set a = a 
where id = 1;
go
select * 
from cdc.dbo_foo_CT
-- empty
go
update dbo.foo 
set a = 'a' 
where id = 1;
go
select * 
from cdc.dbo_foo_CT
-- empty
go
update dbo.foo 
set a = 'x' 
where id = 1;
go
select * 
from cdc.dbo_foo_CT
-- $ops 3 & 4 , valid update bitmask
go
insert dbo.foo 
    (id,a,b,c)
values
    (4,'x','y','z')
go
select * 
from cdc.dbo_foo_CT
-- $op 2 
-- 0x0f bitmask on 4 cols
-- 0x7f bitmask on 7 cols
-- 0xFF bitmask on 8 cols
go
delete 
from dbo.foo
where id = 4;
go
select * 
from cdc.dbo_foo_CT
-- $op 1