How to create sql database trigger

The method to create a sql database trigger is: [create trigger trigger_name on table_name as sql_statement]. A trigger is a special stored procedure that triggers execution when inserting, updating, or deleting operations are performed on the table.

#What is a trigger?

(Recommended learning: mysql tutorial)

A trigger is a special stored procedure that triggers execution when inserting, updating, or deleting a table.

Triggers are generally used to check constraints or process some subsequent transaction logic. The difference between triggers and ordinary stored procedures is that triggers operate on a certain table.

For example: when operations such as update, insert, and delete are performed, the system will automatically call and execute the corresponding trigger on the table. So triggers can be used to implement complex integrity constraints on tables.

Add creation syntax

create trigger trigger_name
　　on {table_name | view_name}
　　{for | After | Instead of }
　　[ insert, update,delete ]
　　as
　　sql_statement

Modify syntax

alter trigger trigger_name--类似于修改表结构

Delete syntax

drop trigger trigger_name

View triggers

select * from sys.triggers
select * from sysobjects where xtype='TR'

View single trigger

exec sp_helptext '触发器名'

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