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Today, the editor will share with you the relevant knowledge about what mysql triggers do. The content is detailed and the logic is clear. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article. Let's take a look.

Description

1. Before writing data, you can forcibly check or convert data, etc.

2. Trigger execution error, the previous successful execution of the SQL will be undone.

Causes the transaction to be rolled back. The trigger name must be unique in the table and can be the same between tables in the database.

Only one trigger is allowed at a time, so the table uses 6 triggers. (before and after insert / before and after update / delete)

3. Safety.

Users can obtain some permissions to operate on the database according to the value of the database. Can track the user's operation to the database.

4. Implement complex non-standard database integrity rules.

Triggers can continuously update related tables in the database. Triggers can reject or restore changes that conflict with related integrity and cancel transactions that attempt to update data. This trigger works when inserting an external key that does not match its primary key.

Example

DELIMITER $CREATE TRIGGER trigger name BEFORE/AFTER INSERT/UPDATE/DELETEON table name [FOR EACH ROW]-row-level trigger BEGIN trigger process body (a set of legal SQL statements) END $DELIMITER; that's all of the article "what are mysql triggers for?" thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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