Is it possible to ensure to block a raw when is selected?

Question

I would like to know if it is posible to ensure block a row when is selected and then not to be able to be selected from another sesión.
I tried xlock, rowloxk but sometimes the second sesión is able to select the row. I can't reproduce this behaviours always, but sometimes happend.
By the moment, the only way to ensure that is doing a fake updating of the row inside a transaction. But this is an extra cost for the database and I would lie to know if there is any other option to ensure the block of the row when is selected.
Thanks.

Answer 1

Hi ComptonAlvaro,
According to my knowledge, it is not possible to lock a row in a SELECT statement and make the row not to be read by another SELECT statement.
A SELECT in SQL Server will place a shared lock on a table row , and a second SELECT would also require a shared lock, these locks are compatible with one another. Therefore, one SELECT cannot block another SELECT.  Although we can lock a row by adding
‘WITH ( XLOCK, ROWLOCK)’ or ‘ WITH (UPDLOCK, TABLOCK)’ in a SELECT statement, another SELECT statement can always get around it by adding a locking hint WITH (NOLOCK) which will provide a dirty read.
For more details, please review the following link:
http://msdn.microsoft.com/EN-US/library/ms187373.aspx
Thanks,
Lydia Zhang