SQL Server 2019

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id	description
1	old data

TRUNCATE TABLE dbo.MyTable_Garbage;
TRUNCATE TABLE dbo.MyTable_Staging;
INSERT dbo.MyTable_Staging(id, description) VALUES(1, 'new data'),(2, 'new row!');

BEGIN TRANSACTION;

ALTER TABLE dbo.MyTable
    SWITCH TO dbo.MyTable_Garbage
    /* we're not allowed to use ABORT_AFTER_WAIT = BLOCKERS on db<>fiddle
    WITH ( WAIT_AT_LOW_PRIORITY 
      ( MAX_DURATION = 1 MINUTES, ABORT_AFTER_WAIT = BLOCKERS )) */;
      
  ALTER TABLE dbo.MyTable_Staging
    SWITCH TO dbo.MyTable;  
    
COMMIT TRANSACTION;

SELECT * FROM dbo.MyTable;

-- now repeat

TRUNCATE TABLE dbo.MyTable_Garbage;
TRUNCATE TABLE dbo.MyTable_Staging;
INSERT dbo.MyTable_Staging(id, description) 
  VALUES(2, 'same old row'),(3, 'another new row!');

BEGIN TRANSACTION;

SELECT * FROM dbo.MyTable;

id	description
1	new data
2	new row!

id	description
2	same old row
3	another new row!