Trigger AFTER INSERT, UPDATE, DELETE to call stored procedure with table name and primary key

For a sync process, my SQL Server database should record a list items that have changed - table name and primary key.

The DB already has a table and stored procedure to do this:

EXEC @ErrCode = dbo.SyncQueueItem "tableName", 1234;

I'd like to add triggers to a table to call this stored procedure on INSERT, UPDATE, DELETE. How do I get the key? What's the simplest thing that could possibly work?

CREATE TABLE new_employees
(
    id_num INT IDENTITY(1,1),
    fname VARCHAR(20),
    minit CHAR(1),
    lname VARCHAR(30)
);
GO

IF OBJECT_ID ('dbo.sync_new_employees','TR') IS NOT NULL 
    DROP TRIGGER sync_new_employees;
GO

CREATE TRIGGER sync_new_employees
ON new_employees
AFTER INSERT, UPDATE, DELETE
AS
     DECLARE @Key Int;
     DECLARE @ErrCode Int;

     --  How to get the key???
     SELECT @Key = 12345; 

     EXEC @ErrCode = dbo.SyncQueueItem "new_employees", @key;
GO

Solution

Not the best solution, but just a direct answer on the question:

SELECT @Key = COALESCE(deleted.id_num,inserted.id_num);

Also not the best way (if not the worst) (do not try this at home), but at least it will help with multiple values:

DECLARE @Key INT;
DECLARE triggerCursor CURSOR LOCAL FAST_FORWARD READ_ONLY 
    FOR SELECT COALESCE(i.id_num,d.id_num) AS [id_num]
        FROM inserted i
        FULL JOIN deleted d ON d.id_num = i.id_num
        WHERE (
                COALESCE(i.fname,'')<>COALESCE(d.fname,'')
             OR COALESCE(i.minit,'')<>COALESCE(d.minit,'')
             OR COALESCE(i.lname,'')<>COALESCE(d.lname,'')
        )
;

OPEN triggerCursor;
FETCH NEXT FROM triggerCursor INTO @Key;
WHILE @@FETCH_STATUS = 0
BEGIN
    EXEC @ErrCode = dbo.SyncQueueItem 'new_employees', @key;
    FETCH NEXT FROM triggerCursor INTO @Key;
END

CLOSE triggerCursor;
DEALLOCATE triggerCursor;

Better way to use trigger based "value-change-tracker":

INSERT INTO [YourTableHistoryName] (id_num, fname, minit, lname, WhenHappened)
SELECT COALESCE(i.id_num,d.id_num) AS [id_num]
    ,i.fname,i.minit,i.lname,CURRENT_TIMESTAMP AS [WhenHeppened]
FROM inserted i
FULL JOIN deleted d ON d.id_num = i.id_num
WHERE ( COALESCE(i.fname,'')<>COALESCE(d.fname,'')
    OR COALESCE(i.minit,'')<>COALESCE(d.minit,'')
    OR COALESCE(i.lname,'')<>COALESCE(d.lname,'')
)
;

The best (in my opinion) way to track changes is to use Temporal tables (SQL Server 2016+)