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This article introduces the relevant knowledge of "how to use mysql trigger". In the operation process of actual cases, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

description

1. Trigger is also a kind of stored procedure program, and the execution SQL statement inside trigger can be operated on multiple lines.

2. In MySQL's stored procedure program, the terminator is defined.

syntax

before/after: whether the trigger is executed before or after the addition, deletion, or modification

delete/insert/update: What actions trigger (add, delete, change)

on table name: which table the trigger monitors (add, delete, modify)

Trigger SQL code block: Executes SQL statements contained in triggers

examples

Create a trigger. When a user purchases a commodity, the corresponding commodity inventory record is updated at the same time. The code is as follows:

--delete trigger, drop trigger name-- if exists drop trigger if exists myty1;--create trigger mytg1-- myty1 trigger name after insert on orders-- orders for each rowinitiateproduct set num = num-new.num where pid=new.pid;end;--insert record into orders values (null,2,1);--Query the update of commodity inventory in the commodity table select * from product; The content of "how to use mysql trigger" is introduced here. Thank you for reading. If you want to know more about industry-related knowledge, you can pay attention to the website. Xiaobian will output more high-quality practical articles for everyone!

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