{"id":2020,"date":"2020-07-29T23:10:13","date_gmt":"2020-07-29T15:10:13","guid":{"rendered":"http:\/\/39.97.231.10\/?p=2020"},"modified":"2020-07-29T23:10:13","modified_gmt":"2020-07-29T15:10:13","slug":"mysql%e8%a7%a6%e5%8f%91%e5%99%a8trigger%e7%9a%84%e4%bd%bf%e7%94%a8","status":"publish","type":"post","link":"http:\/\/www.weijing.co\/?p=2020","title":{"rendered":"MySQL\u89e6\u53d1\u5668trigger\u7684\u4f7f\u7528"},"content":{"rendered":"<div class=\\\"blog_content\\\">\n<div class=\\\"blog_detail\\\">\n<div>\n\u89e6\u53d1\u5668(trigger)\u662f\u6570\u636e\u5e93\u7684\u4e00\u7c7b\u5bf9\u8c61\uff0c\u4e0e\u8868\u5173\u8054\uff0c\u5f53\u8868\u4e2d\u6307\u5b9a\u7684\u4e8b\u4ef6\u53d1\u751f\u65f6\uff0c\u6bd4\u5982\u63d2\u5165\u6570\u636e\uff0c\u66f4\u65b0\u6570\u636e\uff0c\u5220\u9664\u6570\u636e\uff0c\u89e6\u53d1\u5668\u5c31\u4f1a\u88ab\u6fc0\u6d3b\uff0c\u6765\u6267\u884c\u4e00\u4e9bSQL\u8bed\u53e5\u3002<\/p>\n<ul>\n<li>\u89e6\u53d1\u5668\u4e0d\u80fd\u5efa\u7acb\u5728\u4e34\u65f6\u8868\u6216\u8005\u89c6\u56fe\u4e0a\u3002<\/li>\n<li>\u89e6\u53d1\u5668\u7684\u540d\u79f0\u5728schema\u7684\u547d\u540d\u7a7a\u95f4\u91cc\uff0c\u4e5f\u5c31\u662f\u8bf4\u4e00\u4e2a\u6570\u636e\u5e93\u91cc\u9762\u7684\u89e6\u53d1\u5668\u540d\u79f0\u5fc5\u987b\u552f\u4e00\u3002<\/li>\n<li>\u521b\u5efa\u89e6\u53d1\u5668\u7684\u7528\u6237\u9700\u8981\u6709TRIGGER\u6743\u9650\u3002<\/li>\n<\/ul>\n<h4>1. \u89e6\u53d1\u5668\u521b\u5efa\u8bed\u6cd5<\/h4>\n<p>\u521b\u5efa\u89e6\u53d1\u5668\u4f7f\u7528create trigger\u8bed\u6cd5\uff0c\u5982\u4e0b\uff1a<\/p>\n<pre><code>CREATE\n    [DEFINER = user]\n    TRIGGER trigger_name\n    trigger_time trigger_event\n    ON tbl_name FOR EACH ROW\n    [trigger_order]\n    trigger_body\ntrigger_time: { BEFORE | AFTER }\ntrigger_event: { INSERT | UPDATE | DELETE }\ntrigger_order: { FOLLOWS | PRECEDES } other_trigger_name\n<\/code><\/pre>\n<ul>\n<li>trigger_name\uff0c\u89e6\u53d1\u5668\u540d\u79f0\u3002<\/li>\n<li>trigger_time\uff0c\u89e6\u53d1\u65f6\u673a\uff0c\u53ef\u9009\u503c\u4e3aBEFORE\u548cAFTER\uff0c\u8868\u793a\u884c\u6570\u636e\u88ab\u4fee\u6539\u4e4b\u524d\u8fd8\u662f\u4e4b\u540e\u89e6\u53d1\u3002<\/li>\n<li>trigger_event\uff0c\u6fc0\u6d3b\u89e6\u53d1\u5668\u7684\u64cd\u4f5c\u7c7b\u578b\uff0c\u53ef\u9009\u503c\u4e3aINSERT\uff0cUPDATE\u548cDELETE\u3002drop table\uff0ctruncate table \u4ee5\u53ca\u5220\u9664\u5206\u533a\u8868\u5e76\u4e0d\u4f1a\u89e6\u53d1DELETE\u7c7b\u578b\u7684\u89e6\u53d1\u5668\u3002<\/li>\n<li>trigger_order\uff0c\u89e6\u53d1\u5668\u6267\u884c\u987a\u5e8f\uff0c\u5982\u679c\u4e00\u4e2a\u8868\u521b\u5efa\u591a\u4e2a\u76f8\u540c\u64cd\u4f5c\u7c7b\u578b\u7684\u89e6\u53d1\u5668\uff0c\u90a3\u4e48\u8fd9\u4e9b\u89e6\u53d1\u5668\u4f1a\u6309\u7167\u88ab\u521b\u5efa\u7684\u987a\u5e8f\u4f9d\u6b21\u89e6\u53d1\u3002\u53ef\u4ee5\u5728\u521b\u5efa\u89e6\u53d1\u5668\u65f6\uff0c\u6307\u5b9aFOLLOWS\u6216\u8005PRECEDES\u6765\u660e\u786e\u591a\u4e2a\u89e6\u53d1\u5668\u7684\u6267\u884c\u987a\u5e8f\u3002<\/li>\n<li>trigger_body\uff0c\u89e6\u53d1\u5668\u6267\u884c\u4f53\uff0c\u5f53\u89e6\u53d1\u5668\u88ab\u6fc0\u6d3b\u65f6\uff0c\u8981\u6267\u884c\u7684\u8bed\u53e5\u3002\u6267\u884c\u4f53\u4e2d\uff0c\u7528NEW\u6807\u8bc6\u65b0\u7684\u884c\u6570\u636e\uff0cOLD\u6807\u8bc6\u65e7\u7684\u884c\u6570\u636e\u3002<\/li>\n<\/ul>\n<h4>2. \u67e5\u770b\u89e6\u53d1\u5668<\/h4>\n<p>SHOW TRIGGERS\\\\G<br \/>\nSHOW TRIGGERS IN db_name\\\\G<br \/>\nSHOW TRIGGERS IN db_name like \\&#8217;%xxx%\\&#8217;\\\\G<\/p>\n<h4>3. \u5220\u9664\u89e6\u53d1\u5668<\/h4>\n<p>DROP TRIGGER trigger_name;<br \/>\nDROP TRIGGER db_name.trigger_name;<\/p>\n<h4>4. \u89e6\u53d1\u5668\u4f7f\u7528\u6848\u4f8b<\/h4>\n<h5>\u6848\u4f8b\u4e00<\/h5>\n<p>\u6709\u4e00\u5f20\u8868account\uff0c\u5f80\u8fd9\u4e2a\u8868\u63d2\u5165\u6570\u636e\u65f6\uff0c\u5e0c\u671b\u80fd\u591f\u8ba1\u7b97\u6240\u6709\u63d2\u5165\u8bb0\u5f55\u7684amount\u6570\u91cf\u4e4b\u548c\u3002\u91c7\u7528\u89e6\u53d1\u5668\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre><code># \u521b\u5efa\u8868\nCREATE TABLE account (id INT, amount DECIMAL(10,2), primary key(id));\n# \u521b\u5efa\u89e6\u53d1\u5668\nCREATE TRIGGER ins_sum BEFORE INSERT ON account\n       FOR EACH ROW SET @sum = @sum + NEW.amount;\n# \u8ba1\u7b97\u63d2\u5165\u6570\u636e\u4e4b\u548c\nSET @sum = 0;\nINSERT INTO account VALUES(1,14.98),(2,1937.50),(3,-100.00);\nSELECT @sum AS \\'Total amount inserted\\';\n+-----------------------+\n| Total amount inserted |\n+-----------------------+\n|               1852.48 |\n+-----------------------+\n<\/code><\/pre>\n<h5>\u6848\u4f8b\u4e8c<\/h5>\n<p>\u4f7f\u7528\u89e6\u53d1\u5668\u505a\u6570\u636e\u6821\u9a8c\uff0c\u66f4\u65b0account\u8868\u4e2d\u7684amount\u5b57\u6bb5\uff0camount\u5b57\u6bb5\u53d6\u503c\u53ea\u80fd\u57280~100\u4e4b\u95f4\uff0c\u5176\u4f59\u7684\u503c\u90fd\u662f\u65e0\u6548\u503c\uff0c\u5c0f\u4e8e0\u7684\u503c\u81ea\u52a8\u7ea0\u6b63\u4e3a0\uff0c\u5927\u4e8e100\u7684\u503c\u81ea\u52a8\u7ea0\u6b63\u4e3a100\uff0c\u91c7\u7528\u89e6\u53d1\u5668\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre><code>mysql&gt; delimiter \/\/\nmysql&gt; CREATE TRIGGER upd_check BEFORE UPDATE ON account\n       FOR EACH ROW\n       BEGIN\n           IF NEW.amount &lt; 0 THEN\n               SET NEW.amount = 0;\n           ELSEIF NEW.amount &gt; 100 THEN\n               SET NEW.amount = 100;\n           END IF;\n       END;\/\/\nmysql&gt; delimiter ;\n<\/code><\/pre>\n<h5>\u6848\u4f8b\u4e09<\/h5>\n<p>\u4f7f\u7528\u89e6\u53d1\u5668\u5b9e\u73b0\u5f71\u5b50\u8868\uff0c\u5bf9account\u8868\u7684\u6240\u6709\u64cd\u4f5c\uff0c\u90fd\u4f1a\u540c\u6b65\u5230\u5f71\u5b50\u8868account_shadow\u4e2d\u3002<\/p>\n<pre><code># \u521b\u5efa\u5f71\u5b50\u8868\nmysql&gt; create table account_shadow like account;\nmysql&gt; delimiter \/\/\n# \u521b\u5efainsert\u89e6\u53d1\u5668\nmysql&gt; CREATE TRIGGER trg_insert after INSERT ON account\n  FOR EACH ROW\n  BEGIN\n    INSERT INTO account_shadow SET id=NEW.id, amount=NEW.amount;\n  END;\n# \u521b\u5efaupdate\u89e6\u53d1\u5668\n  CREATE TRIGGER trg_update after UPDATE ON account\n  FOR EACH ROW\n  BEGIN\n    update account_shadow SET id=NEW.id, amount=NEW.amount where id=OLD.id;\n  END;\n# \u521b\u5efadelete\u89e6\u53d1\u5668\n  CREATE TRIGGER trg_delete after DELETE ON account\n  FOR EACH ROW\n  BEGIN\n    delete from account_shadow where id=OLD.id;\n  END;\/\/\nmysql&gt; delimiter ;\n<\/code><\/pre>\n<h4>5. \u89e6\u53d1\u5668\u53ef\u80fd\u5bfc\u81f4\u7684\u95ee\u9898<\/h4>\n<ol>\n<li>\u89e6\u53d1\u5668\u5bf9\u6570\u636e\u5e93\u6027\u80fd\u4e00\u5b9a\u7684\u635f\u8017\uff0c\u5efa\u8bae\u4f7f\u7528\u524d\u8fdb\u884c\u538b\u6d4b\uff0c\u5224\u65ad\u6027\u80fd\u4e0d\u5f71\u54cd\u6b63\u5e38\u4e1a\u52a1\u65f6\u518d\u4f7f\u7528\u3002<\/li>\n<li>\u89e6\u53d1\u5668\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6b7b\u9501\uff0c\u5728\u9ad8\u5e76\u53d1\u4e1a\u52a1\u4e0b\uff0c\u8fc7\u591a\u5730\u4f7f\u7528\u89e6\u53d1\u5668\uff0c\u5c06\u4f1a\u5927\u5927\u589e\u52a0\u6b7b\u9501\u7684\u6982\u7387\u3002\u89e6\u53d1\u5668\u5b9e\u73b0\u5728MySQL\u5185\u90e8\uff0c\u5bf9\u5ba2\u6237\u7aef\u4e0d\u53ef\u89c1\uff0c\u5bfc\u81f4\u6b7b\u9501\u65f6\uff0c\u4e5f\u66f4\u4e0d\u5bb9\u6613\u88ab\u53d1\u73b0\u3002<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u89e6\u53d1\u5668(trigger)\u662f\u6570\u636e\u5e93\u7684\u4e00\u7c7b\u5bf9\u8c61\uff0c\u4e0e\u8868\u5173\u8054\uff0c\u5f53\u8868\u4e2d\u6307\u5b9a\u7684\u4e8b\u4ef6\u53d1\u751f\u65f6\uff0c\u6bd4\u5982\u63d2\u5165\u6570\u636e\uff0c\u66f4\u65b0\u6570\u636e\uff0c\u5220\u9664\u6570\u636e &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"http:\/\/www.weijing.co\/?p=2020\"> <span class=\"screen-reader-text\">MySQL\u89e6\u53d1\u5668trigger\u7684\u4f7f\u7528<\/span> \u67e5\u770b\u5168\u6587 &raquo;<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":""},"categories":[90,88],"tags":[],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false,"mailpoet_newsletter_max":false,"woocommerce_thumbnail":false,"woocommerce_single":false,"woocommerce_gallery_thumbnail":false,"shop_catalog":false,"shop_single":false,"shop_thumbnail":false},"uagb_author_info":{"display_name":"weijing","author_link":"http:\/\/www.weijing.co\/?author=4"},"uagb_comment_info":0,"uagb_excerpt":"\u89e6\u53d1\u5668(trigger)\u662f\u6570\u636e\u5e93\u7684\u4e00\u7c7b\u5bf9\u8c61\uff0c\u4e0e\u8868\u5173\u8054\uff0c\u5f53\u8868\u4e2d\u6307\u5b9a\u7684\u4e8b\u4ef6\u53d1\u751f\u65f6\uff0c\u6bd4\u5982\u63d2\u5165\u6570\u636e\uff0c\u66f4\u65b0\u6570\u636e\uff0c\u5220\u9664\u6570\u636e&hellip;","_links":{"self":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts\/2020"}],"collection":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2020"}],"version-history":[{"count":0,"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts\/2020\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2020"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2020"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2020"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}