how to make a trigger in sql code example

Example 1: CREATE trigger SQL

-- Oracle DB Syntax
CREATE OR REPLACE TRIGGER {trigger_name} 
BEFORE | AFTER 
INSERT | UPDATE | DELETE 
ON {table_name}
(FOR EACH ROW) 
{operation to be executed}

-- for example
CREATE TRIGGER log_updates 
AFTER INSERT OR UPDATE ON Person
FOR EACH ROW 
INSERT INTO LogPerson(ts, IdPerson, surname)
VALUES(CURRENT_TIMESTAMP, NEW.id, NEW.surname);

Example 2: how use trigger in sql

CREATE TRIGGER Product_Details_tr 
BEFORE INSERT ON Product_Details 
FOR EACH ROW 
SET NEW.User_ID = CURRENT_USER();

Example 3: SQL trigger

CREATE TRIGGER [schema_name.]trigger_name
ON table_name
{FOR | AFTER | INSTEAD OF} {[INSERT] [,] [UPDATE] [,] [DELETE]}
AS
{sql_statements}