Problem

Write a trigger that will update the "last_updated" column in a table every time a row is inserted or updated.
Example input:
Insert into table (id, name, last_updated) values (1, 'John', '2019-01-01');
Output:
The "last_updated" column in the table is updated to the current date and time.

Solution

CREATE TRIGGER update_last_updated
AFTER INSERT OR UPDATE ON table
FOR EACH ROW
BEGIN
    UPDATE table
    SET last_updated = CURRENT_TIMESTAMP
    WHERE id = NEW.id;
END;

/*

The trigger is optimal because it only updates the last_updated column for the row that was inserted or updated.

*/