What does Mysql transaction commit and transaction rollback mean?

This article mainly introduces you to the relevant knowledge of mysql transaction submission and transaction rollback.

A transaction can be said to be a batch of sql statements, but this batch is an atom and indivisible. Either all of them are submitted for execution, or rollback (rollback) is not executed. Regarding the detailed definition of transactions, we have introduced it to you in previous articles. Friends who need it can refer to it first.

【What does transaction mean in mysql data table】

【How to open transaction in Mysql data table】

So what does transaction commit and transaction rollback here mean? How to achieve it?

Below we will give you a detailed explanation with some simple examples.

1. Transaction submission (commit)

Successfully ends, all DML (insert, update, delete) statement operation history and underlying hard disk Data is synchronized once.

For example, there is a table called money, which contains two pieces of data. The amounts with ID 1 and ID 2 are 7000 and 8000 respectively.

#Then we start the transaction through the "start transaction" statement.

Then perform some update operations on the data in the table, as shown in the figure below, we increase the amount of the person with id 1 and id 2 in the table respectively. 5000.

Then in our previous article [How to enable manual transactions in Mysql data tables], we mentioned that after the transaction is enabled and then the data is updated, the database The real data will not change, only the records will be updated to the transaction log. If we want the data to be updated synchronously into the database, we need to perform a transaction commit operation.

Here you need to master the syntax of transaction submission:

commit;

After the transaction is submitted, we will use Navicat to check whether the data in the data table has occurred Variety.

#As shown in the figure, the real table data can only be changed after the transaction is submitted and confirmed.

2. Transaction rollback (rollback)

If the transaction fails, all DML statement operation history records will be cleared.

After performing the above transaction submission operation, the data in the money table has changed to 12000 and 13000.

Here we reopen the transaction and perform a series of update data operations.

Basic syntax for transaction rollback:

rollback;

Then we can find from the figure that when After we perform a transaction rollback operation, a series of operations after starting the transaction will be cleared, which means that after the transaction rollback is performed, the data in the database will still not change.

Note: If all the sql statements in the transaction are executed correctly, you need to manually submit the commit; otherwise, if there is any execution error, you need to submit a rollback yourself, and all operations will be rolled back. Instead of commit, you will be automatically judged and rolled back.

This article is an introduction to the relevant knowledge about manual transaction submission and transaction rollback of mysql data tables. It is easy to understand and I hope it will be helpful to friends in need!

If you want to know more about mysql, you can follow the PHP Chinese website mysql video tutorial, everyone is welcome to refer to and learn!

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