Thanks for reply,here is my code
-- Random Respawn
DELETE FROM `pool_template` WHERE entry=888002;
INSERT INTO `pool_template`(`entry`,`max_limit`,`description`) VALUES
(888002,1, 'NPC Event Spawn (888002)');
DELETE FROM `pool_creature` WHERE pool_entry=888002;
INSERT INTO `pool_creature`(`guid`,`pool_entry`,`chance`,`description`) VALUES
(400000,888002,0, 'NPC Event Spawn 1'),
(400001,888002,0, 'NPC Event Spawn 2'),
(400002,888002,0, 'NPC Event Spawn 3');
-- Game Event ID: 100
DELETE FROM game_event WHERE eventEntry IN (100);
INSERT INTO game_event VALUES
(100,'2015-03-16 21:46:00','2015-03-16 22:40:00',120,119,0,'Event Killing Mob',0);
-- Game Event Creature
DELETE FROM game_event_creature WHERE guid IN (400000,400001,400002);
INSERT INTO game_event_creature VALUES
(100,400000),
(100,400001),
(100,400002);
-- Game Event Pool
DELETE FROM game_event_pool WHERE eventEntry IN (100);
INSERT INTO game_event_pool VALUES
(100,888002);