MySQL and transactions

[Fabrice FRASSAINT]

Hello,

Does someone knows how transactions are made in MySQL on Berkeley DB
type tables ???

I need to insert a new entry in a table but one of its field is an
order field so i use the MAX of current entries in the table.
To lock tables to be sure that 2 persons can't have the same MAX at
the same time, I use transactions.
Nevertheless, How to be sure to get a WRITE lock on this table if my
first statement is a select ?
I'm doing this :

BEGIN;
SELECT MAX(ESSAILOCK_ORDER) AS MAX FROM ESSAILOCK;
INSERT INTO ESSAILOCK (ESSAILOCK_TITRE;ESSAILOCK_ORDER) VALUES
('essai3',MAX);
COMMIT;

If the select is in first, am i just getting a reading lock, which
could allow someone else to insert a new entry with higher order
maybe.
Do I havbe to start with a fake update on the table to get a write
lock ????
Thanks in advance for any help