when can we use trigger in mysql code example

Example 1: trigger in mysql syntax

CREATE TRIGGER trigger_name
{BEFORE | AFTER} {INSERT | UPDATE| DELETE }
ON table_name FOR EACH ROW
trigger_body;

Example 2: mysql create trigger

CREATE
    TRIGGER `event_name` BEFORE/AFTER INSERT/UPDATE/DELETE
    ON `database`.`table`
    FOR EACH ROW BEGIN
		-- trigger body
		-- this code is applied to every 
		-- inserted/updated/deleted row
    END;
    
CREATE
	TRIGGER `blog_after_insert` AFTER INSERT 
	ON `blog` 
	FOR EACH ROW BEGIN
	
		IF NEW.deleted THEN
			SET @changetype = 'DELETE';
		ELSE
			SET @changetype = 'NEW';
		END IF;
    
		INSERT INTO audit (blog_id, changetype) VALUES (NEW.id, @changetype);
		
    END$$