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This article mainly explains "what are the characteristics of MySQL transaction". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the characteristics of MySQL transaction".

What are the characteristics of MySQL transaction

Atomicity (atomicity) Consistency (stability, consistency) Isolation (isolation) Durability (reliability)

Note: transactions are valid only for statements that affect the data.

Showengines// looks at the data engines supported by mysql locks.

MyISAM does not support things, InnoDB supports things.

By default, MySQL will run in autocommit mode, which means that no small command will be executed as if there was only one command.

If you want mysql to support transactions, you only need to modify the data engine (altertablepersontype=INNODB).

Use the starttransaction or begin command to open a thing, and use commit, or rollback, to end it.

The end of things: things end not only with commit,rollback, but also with DDL or DCL statements.

Save point: through the save point mechanism: users can set some save points in things with the savepointname command. Later, when users use rollbacktosavepointname to end things, the data before name is saved, and the data after that is not saved.

Mysql uses keywords for transactions

Begin// opens a transaction. Commit// is submitted to the database. Rollback// cancels the operation. Savepoint// save, partially cancel, partially submit. Altertablepersontype=INNODB// modifies the data engine.

Example:

Beginupdatepersonsetname='efgh'whereid=10select*frompersonrollbackselect*fromperson

Example:

Altertablepersontype=INNODBbeginupdatepersonsetname='efgh'whereid=10select*frompersoncommitselect*frompersonbegindeletefrompersonwhereid=21updatepersonsetname='efgh'whereid=10commit/rollback

SavePoint must be used for the above partial submission.

What are the considerations for saving MySQL transactions?

1. Can only be canceled to a SavePoint rollbacktosavepointp1.

two。 Cannot submit some saved committosavepointp2// misspelling.

3. Finally, commit removes the uncanceled SavePoint from submitting to the data.

Examples of transaction SavePoint usage:

Begin;updatescoresetscore=40wherescoreid=1;savepoints1;updatescoresetscore=50wherescoreid=2;select*fromscore;rollbacktosavepoints1;select*fromscore;commit

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