In Oracle database, you can use the CREATE TRIGGER statement to add triggers. A trigger is a database object that can define one or more events on a database table and automatically perform corresponding actions when the event occurs.
In Oracle database, you can use the CREATE TRIGGER statement to add triggers. A trigger is a database object that can define one or more events on a database table and automatically perform corresponding actions when the event occurs.
Here is an example of creating a trigger:
sql
CREATE?TRIGGER?trigger_name?? BEFORE?INSERT?ON?table_name?? FOR?EACH?ROW?? BEGIN?? ????--?觸發(fā)器邏輯?? ????--?在這里編寫觸發(fā)器要執(zhí)行的SQL語句或邏輯?? END;
In the above example, you need to replace the following:
trigger_name: trigger The name of the device, you can customize the name according to your needs.
BEFORE INSERT: Specifies that the trigger fires before the insert operation. You can select other events according to your needs, such as AFTER UPDATE, BEFORE DELETE, etc.
table_name: The name of the table on which to apply the trigger.
FOR EACH ROW: Specify the trigger as a row-level trigger, which will trigger every insertion. You can omit this keyword if you want to trigger on table level.
The part between BEGIN and END is the logic of the trigger. Here you can write SQL statements or stored procedures to be executed.
Please note that trigger logic can use SQL statements, PL/SQL code, and other database objects (such as stored procedures and functions).
In addition to the above examples, you can also add other logic according to your needs, such as checking constraints, updating other tables, etc. The specific implementation of triggers depends on your business needs and logic.
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