INSERT INTO taskHistory (taskId, createdDateTime, taskStatusId, createdByUserId, assignedToUserId, showUpdateToUser, comment)
SELECT id, dateCreated, taskStatusId, createdByUserId, assignedToUserId, 0, 'Task created'
FROM task WHERE id NOT IN (SELECT taskId FROM taskhistory);

UPDATE task
SET lastTaskHistoryId = (SELECT MAX(id) FROM taskHistory WHERE taskId = task.id)
WHERE IFNULL(lastTaskHistoryId, 0) = 0;