add last_modified column to an sqlite3 database

gistfile1.txt

ALTER TABLE your_table
ADD COLUMN last_update TEXT;

CREATE TRIGGER update_last_update
         AFTER UPDATE
            ON Your_Table_Name
      FOR EACH ROW
BEGIN
    UPDATE Your_Table_Name
       SET last_update = CURRENT_TIMESTAMP
     WHERE id = NEW.id;
END;

PRAGMA recursive_triggers = OFF;