01 | MySQL transaction processing

MySQL Management Transactions

This paper describes how to use COMMITand ROLLBACKstatement transaction management

Transaction Processing

What transactions are?

• Maintain database integrity
• Batch SQL statement, either all executed or not executed

Transaction What is the role?

Transactions can use to ensure that a set of operations will not stop halfway, or perform them as a whole, or simply do not perform.

If an error occurs, then fall back to a known safe state

Several important terms

the term
Transaction (transaction)	It refers to a group of sql statement
Rollback (rollback)	It refers to the process of revocation of sql statement
Submit (commit)	It refers to data not stored in the result table write sql
Retention point (save point)	Transaction set during a temporary placeholder can publish their fallback

Control Transactions

• Use rollback roll back a transaction

# 事务开始
START TRANSACTION;
DELETE FROM ordertotals;
SELECT * FROM ordertotals;
ROLLBACK;

SELECT * FROM ordertotals;

rollbackCan only be used in a transaction,start transaction

• Use commit to commit the transaction

# 26.2.2 使用COMMIT
START TRANSACTION;
DELETE FROM orderitems WHERE order_num=20010;
DELETE FROM orders WHERE order_num=20010;
COMMIT ;

• Use a reserved spot savepoint

SAVEPOINT delete1;
-- 回退
ROLLBACK delete1;

• Change the default submit behavior

Mysql default behavior is to automatically submit the changes, the changes take effect immediately, but you can not automatically submit the changes set

SET autocommit=0;

Up autocommitto 1, before submitting changes