我需要在我的 MySQL 项目中使用事务。但我不确定是否必须使用 mysql_query("SET AUTOCOMMIT=0");
或不。
我知道我有 2 个选择:
- 开始
- 开始交易
我还听说这两项中的一项不需要使用 AUTOCOMMIT = 0
。
请帮助我知道什么时候我必须使用 AUTOCOMMIT = 0
实际使用 BEGIN
或 START TRANSACTION
?
谢谢。
最佳答案
如 the manual 中所述:
By default, MySQL runs with autocommit mode enabled. This means that as soon as you execute a statement that updates (modifies) a table, MySQL stores the update on disk to make it permanent. The change cannot be rolled back.
To disable autocommit mode implicitly for a single series of statements, use the
START TRANSACTION
statement:START TRANSACTION; SELECT @A:=SUM(salary) FROM table1 WHERE type=1; UPDATE table2 SET summary=@A WHERE type=1; COMMIT;
With
START TRANSACTION
, autocommit remains disabled until you end the transaction withCOMMIT
orROLLBACK
. The autocommit mode then reverts to its previous state.
手册接着说:
To disable autocommit mode explicitly, use the following statement:
SET autocommit=0;
After disabling autocommit mode by setting the
autocommit
variable to zero, changes to transaction-safe tables (such as those forInnoDB
orNDBCLUSTER
) are not made permanent immediately. You must useCOMMIT
to store your changes to disk orROLLBACK
to ignore the changes.
autocommit
is a session variable and must be set for each session. To disable autocommit mode for each new connection, see the description of theautocommit
system variable at Section 5.1.3, “Server System Variables”.
BEGIN
andBEGIN WORK
are supported as aliases ofSTART TRANSACTION
for initiating a transaction.START TRANSACTION
is standard SQL syntax and is the recommended way to start an ad-hoc transaction.
关于使用 BEGIN 和 START TRANSACTION 时 MySQL AUTOCOMMIT 状态,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11375890/