本文實(shí)例講述了MySQL觸發(fā)器簡(jiǎn)單用法。分享給大家供大家參考，具體如下：
mysql觸發(fā)器和存儲(chǔ)過程一樣，是嵌入到mysql的一段程序，觸發(fā)器是由事件來觸發(fā)的，這些事件包括，INSERT,UPDATE,DELETE，不包括SELECT
創(chuàng)建觸發(fā)器
CREATE TRIGGER name,time,event ON table_name FOR EACH ROW trigger_stmt
例如
有多個(gè)執(zhí)行語句的觸發(fā)器
CREATE TABLE test1(a1 INT);CREATE TABLE test2(a2 INT);CREATE TABLE test3(a3 INT NOT NULL AUTO_INCREMENT PRIMARY KEY);CREATE TABLE test4( a4 INT NOT NULL AUTO_INCREMENT PRIMARY KEY, b4 INT DEFAULT 0);DELIMITER //CREATE TRIGGER testref BEFORE INSERT ON test1 FOR EACH ROW BEGIN INSERT INTO test2 SET a2 = NEW.a1; DELETE FROM test3 where a3 = NEW.a1; UPDATE test4 SET b4 = b4 + 1 WHERE a4 = NEW.a1; END //DELIMITER ;INSERT INTO test3(a3) VALUES (NULL), (NULL), (NULL), (NULL), (NULL), (NULL),(NULL), (NULL), (NULL), (NULL), (NULL), (NULL);INSERT INTO test4(a4) VALUES (0), (0), (0), (0), (0), (0), (0), (0), (0), (0);//開始測(cè)試INSERT INTO test1 VALUES (1), (3), (1), (7), (1), (8), (4), (4);
查看觸發(fā)器
SHOW TRIGGERS /G; //查看所有SELECT * FROM information_schema.TRIGGERS where TRIGGER_NAME = 'testref';
刪除觸發(fā)器
DROP TRIGGER testref;
綜合案例
步驟1：創(chuàng)建persons表
CREATE TABLE persons (name VARCHAR(40), num int);
步驟2：創(chuàng)建一個(gè)銷售額表sales
CREATE TABLE sales (name VARCHAR(40), sum int);
步驟3：創(chuàng)建一個(gè)觸發(fā)器
CREATE TRIGGER num_sum AFTER INSERT ON personsFOR EACH ROW INSERT INTO sales VALUES (NEW.name,7*NEW.num);
步驟4：向persons表中插入記錄
INSERT INTO persons VALUES ('xiaoxiao',20),('xiaohua',69);SELECT * FROM persons;SELECT *FROM sales;希望本文所述對(duì)大家MySQL數(shù)據(jù)庫計(jì)有所幫助。
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