Question

I’m converting a webapp from mysql to SQL Server. Now I want to convert the following code (this is a simplified version):

LOCK TABLES media WRITE, deleted WRITE;
INSERT INTO deleted (stuff) SELECT stuff FROM media WHERE id=1 OR id=2;
DELETE FROM media WHERE id=1 OR id=2;
UNLOCK TABLES;

Because I’m copying stuff which is going to be deleted I want to make sure any reads to ‘media’ or ‘deleted’ will wait until this whole operation is ready. Otherwise these reads will see stuff that isnt there anymore a sec later.

How can I replicate this behavior in SQL Server? I read some pages on transactions and isolation levels but I can’t figure out if I can disable any read to table ‘media’ and ‘deleted’ (or on row-level).

Thanx!

Answer 1

You could use lock hints in your query. If you specify a table lock and hold it until the end of the transaction, that should be equivalent.

begin transaction;

INSERT INTO deleted
   SELECT stuff FROM media WITH (tablock holdlock)
   WHERE id = 1 or id = 2;

DELETE FROM media where id = 1 or id = 2;

commit;