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How do I create a trigger? In view of this problem, this article gives the corresponding analysis and answers, hoping to help more friends who want to solve this problem to find a more simple and feasible way.

What is a trigger?

Triggers are used to perform some actions "automatically" after / before certain actions. (for example, if new student information is inserted, then the number of students should be modified in the class table).

When insert delete update sets the trigger, performing the insert delete update operation automatically triggers the contents of the setting.

A table can have up to six triggers (3x2, three operations * two times (before | after)).

Create trigger

Syntax:

Create trigger trigger name before | after event on table name for each row trigger statement

The trigger name is recommended to be trigger_xxx so that it is easy to distinguish and the trigger name cannot be duplicated.

Before | after represents the trigger statement execution time. In the case of before, the trigger statement is executed before the insert delete update operation; after is after.

The event is one of the insert delete update operations.

For each row is a trigger that performs the corresponding action on behalf of any record.

The trigger statement is the statement to be executed when the trigger is triggered.

After reading the above, do you have any further understanding of creating triggers? If you want to know more about it, you are welcome to follow the industry information channel. Thank you for reading.

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