Daniel

1. at any transaction level. this is storage engine, innodb has row lock.

2. create table in mysql. create table lc (id integer primary key,text varchar(200));

3. insert a new data in lc; insert into lc values(1,’first’);

session 1	session 2
insert into lc values(1,’first’);
	select * from lc; result:(1,’first’)
start transaction;
	start transaction;
update lc set text = ‘second’ where id = 1 and text = ‘first’;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 0 Warnings: 0
	update lc set text = ‘thrid’ where id = 1 and text = ‘first’;
	result: waiting…
commit;
	Query OK, 0 rows affected (4.94 sec[waiting time])
	Rows matched: 0 Changed: 0 Warnings: 0
	commit;