DELETE from MyRecords
WHERE tag = 1
OR tag = 2
OR longTag = 'LongTag1'
OR tag = 555

delete real_table from real_table a
   join u_real_table b on (a.tag = b.tag);
insert into real_table select *
   from u_real_table where tag is not null;

delete real_table from real_table a
   join u_real_table b on (a.longTag = b.longTag);
insert into real_table select *
   from u_real_table where longTag is not null;

delete from u_real_table;

CREATE TRIGGER dbo.TR_MyTable_Merge
   ON  dbo.MyTable
   INSTEAD OF INSERT
AS
BEGIN
  SET NOCOUNT ON;

  BEGIN TRANSACTION

  DELETE MyTable
  FROM   MyTable t INNER JOIN inserted i ON t.tag = i.tag

  DELETE MyTable
  FROM   MyTable t INNER JOIN inserted i ON t.longTag = i.longTag

  INSERT MyTable
  SELECT * FROM inserted

  COMMIT TRANSACTION

  SET NOCOUNT OFF;
END

DELETE FROM MyRecords
WHERE  tag IN (1, 2, 555) -- build a list
OR longTag IN ('LongTag1')

DELETE from MyRecords
WHERE tag = 1

DELETE from MyRecords
WHERE tag = 2

DELETE from MyRecords
WHERE tag = 555

DELETE from MyRecords
WHERE longTag = 'LongTag1'

DECLARE @tag TABLE (id INT);
DECLARE @longTag TABLE (id VARCHAR(50));

INSERT
INTO  @tag
VALUES (`tag1`)

INSERT
INTO  @tag
VALUES (`tag2`)

/* ... */

INSERT INTO @longTag
VALUES ('LongTag1')

/* ... */


DELETE
FROM    MyRecords r
WHERE   r.tag IN (SELECT * FROM @tag)
        OR r.longTag IN (SELECT * FROM @longTag)

DELETE
FROM    MyRecords r
WHERE   r.tag IN (SELECT * FROM @tag)

DELETE
FROM    MyRecords r
WHERE   r.longTag IN (SELECT * FROM @longTag)