mysql觸發器

• 時間點：before/after
• 觸發事件： update/delete/insert
• 時間點+觸發事件：構成一個完整的觸發器的觸發時機；
• 一個觸發時機最多只能由1個Trigger：如 before-insert最多只能有1個觸發器，如果需要多個，需要在1個Trigger內些sql Statement；

old和new

• insert：只有new關鍵字可以使用；
• update: new和old關鍵字都可以使用；
• delete: 只有old關鍵字可以使用；

完整語句

CREATE TABLE `capacity_pm` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT ‘自增主鍵‘,
  `pool_id` char(36) CHARACTER SET utf8 DEFAULT NULL COMMENT ‘資源池ID‘,
  `cluster_lv1` varchar(255) CHARACTER SET utf8 DEFAULT NULL COMMENT ‘集群分類‘,
  `cluster_lv2` varchar(255) CHARACTER SET utf8 DEFAULT NULL COMMENT ‘集群2級分類‘,
  `update_at` datetime DEFAULT CURRENT_TIMESTAMP COMMENT ‘更新或創建時間‘,
  `templete_id` varchar(255) CHARACTER SET utf8 NOT NULL COMMENT ‘模板ID‘,
  `templete_name` varchar(255) CHARACTER SET utf8 DEFAULT NULL COMMENT ‘模板名稱‘,
  `templete_cpu_core` int(10) unsigned zerofill NOT NULL COMMENT ‘模板CPU核數‘,
  `templete_mem_size` double NOT NULL COMMENT ‘模板內存大小‘,
  `templete_disk_size` double NOT NULL COMMENT ‘模板磁盤大小‘,
  `host_total` int(11) unsigned zerofill DEFAULT NULL COMMENT ‘主機總數‘,
  `host_used` int(11) unsigned zerofill DEFAULT NULL COMMENT ‘主機已分配數量‘,
  `cpu_core_total` int(11) unsigned zerofill DEFAULT NULL COMMENT ‘cpu總核數‘,
  `cpu_core_free` int(11) DEFAULT NULL,
  `cpu_core_used` int(11) DEFAULT NULL COMMENT ‘cpu已分配數量‘,
  `cpu_core_util` double(10,3) DEFAULT NULL COMMENT ‘cpu核數使用占比‘,
  `mem_total` double DEFAULT NULL COMMENT ‘內存總空間‘,
  `mem_free` double DEFAULT NULL,
  `mem_used` double DEFAULT NULL,
  `mem_util` double DEFAULT NULL COMMENT ‘內存使用占比‘,
  `disk_total` double DEFAULT NULL,
  `disk_free` double DEFAULT NULL,
  `disk_used` double DEFAULT NULL,
  `disk_util` double DEFAULT NULL COMMENT ‘磁盤使用占比‘,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_templete_all` (`pool_id`,`templete_id`) USING BTREE COMMENT ‘模塊ID做完整索引‘
) ENGINE=InnoDB AUTO_INCREMENT=101 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

CREATE TRIGGER `pm_before_insert_trigger` BEFORE INSERT ON `capacity_pm` FOR EACH ROW begin
set new.cpu_core_total=new.host_total * new.templete_cpu_core;
set new.cpu_core_used=new.host_used * new.templete_cpu_core;
set new.cpu_core_free=new.cpu_core_total - new.cpu_core_used;
set new.cpu_core_util=new.cpu_core_used / new.cpu_core_total;
end;

CREATE TRIGGER `pm_before_update_trigger` BEFORE UPDATE ON `capacity_pm` FOR EACH ROW begin
set new.cpu_core_total=new.host_total * old.templete_cpu_core;
set new.cpu_core_used=new.host_used * old.templete_cpu_core;
set new.cpu_core_free=new.cpu_core_total - new.cpu_core_used;
set new.cpu_core_util=new.cpu_core_used / new.cpu_core_total;
end;
 

創建觸發器的語句

CREATE TRIGGER `pm_before_insert_trigger` BEFORE INSERT ON `capacity_pm` FOR EACH ROW begin
set new.cpu_core_total=new.host_total * new.templete_cpu_core;
set new.cpu_core_used=new.host_used * new.templete_cpu_core;
set new.cpu_core_free=new.cpu_core_total - new.cpu_core_used;
set new.cpu_core_util=new.cpu_core_used / new.cpu_core_total;
end;

CREATE TRIGGER `pm_before_update_trigger` BEFORE UPDATE ON `capacity_pm` FOR EACH ROW begin
set new.cpu_core_total=new.host_total * old.templete_cpu_core;
set new.cpu_core_used=new.host_used * old.templete_cpu_core;
set new.cpu_core_free=new.cpu_core_total - new.cpu_core_used;
set new.cpu_core_util=new.cpu_core_used / new.cpu_core_total;
end;
 

參考

mysql5.6-trigger官網

【mysql】mysql觸發器使用示例