{"id":870,"date":"2025-02-18T19:40:46","date_gmt":"2025-02-18T11:40:46","guid":{"rendered":"https:\/\/eve2333.top\/?p=870"},"modified":"2025-02-18T19:40:47","modified_gmt":"2025-02-18T11:40:47","slug":"mysql%e6%95%b0%e6%8d%ae%e5%ba%93%e5%85%a5%e9%97%a8%e5%88%b0%e5%a4%a7%e8%9b%87%e5%b0%9a%e7%a1%85%e8%b0%b7%e5%ae%8b%e7%ba%a2%e5%ba%b7%e8%80%81%e5%b8%88%e7%ac%94%e8%ae%b0-%e5%9f%ba%e7%a1%80%e7%af%87-p-12","status":"publish","type":"post","link":"https:\/\/eve2333.top\/?p=870","title":{"rendered":"MySQL\u6570\u636e\u5e93\u5165\u95e8\u5230\u5927\u86c7\u5c1a\u7845\u8c37\u5b8b\u7ea2\u5eb7\u8001\u5e08\u7b14\u8bb0 \u57fa\u7840\u7bc7 part 16"},"content":{"rendered":"\n<p>\u200b<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">&nbsp;\u7b2c16\u7ae0_\u53d8\u91cf\u3001\u6d41\u7a0b\u63a7\u5236\u4e0e\u6e38\u6807<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">1.1 \u7cfb\u7edf\u53d8\u91cf<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1.1.1 \u7cfb\u7edf\u53d8\u91cf\u5206\u7c7b<\/h3>\n\n\n\n<p>&nbsp;\u53d8\u91cf\u7531\u7cfb\u7edf\u5b9a\u4e49\uff0c\u4e0d\u662f\u7528\u6237\u5b9a\u4e49\uff0c\u5c5e\u4e8e \u670d\u52a1\u5668\u5c42\u9762\u3002\u542f\u52a8MySQL\u670d\u52a1\uff0c\u751f\u6210MySQL\u670d\u52a1\u5b9e\u4f8b\u671f\u95f4\uff0c MySQL\u5c06\u4e3aMySQL\u670d\u52a1\u5668\u5185\u5b58\u4e2d\u7684\u7cfb\u7edf\u53d8\u91cf\u8d4b\u503c\uff0c\u8fd9\u4e9b\u7cfb\u7edf\u53d8\u91cf\u5b9a\u4e49\u4e86\u5f53\u524dMySQL\u670d\u52a1\u5b9e\u4f8b\u7684\u5c5e\u6027\u3001\u7279\u5f81\u3002\u8fd9\u4e9b\u7cfb\u7edf\u53d8\u91cf\u7684\u503c\u8981\u4e48\u662f \u7f16\u8bd1MySQL\u65f6\u53c2\u6570 \u7684\u9ed8\u8ba4\u503c\uff0c\u8981\u4e48\u662f\u503c\u3002<\/p>\n\n\n\n<p>\u7cfb\u7edf\u53d8\u91cf\u5206\u4e3a\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\uff08\u9700\u8981\u6dfb\u52a0 global \u5173\u952e\u5b57\uff09\u4ee5\u53ca\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\uff08\u9700\u8981\u6dfb\u52a0 session \u5173\u952e \u5b57\uff09\uff0c\u6709\u65f6\u4e5f\u628a\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u7b80\u79f0\u4e3a\u5168\u5c40\u53d8\u91cf\uff0c\u6709\u65f6\u4e5f\u628a\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u79f0\u4e3alocal\u53d8\u91cf\u3002\u5982\u679c\u4e0d\u5199\uff0c\u9ed8\u8ba4\u4f1a\u8bdd\u7ea7\u522b\u3002\u9759\u6001\u53d8\u91cf\uff08\u5728 MySQL \u670d\u52a1\u5b9e\u4f8b\u8fd0\u884c\u671f\u95f4\u5b83\u4eec\u7684\u503c\u4e0d\u80fd\u4f7f\u7528 set \u52a8\u6001\u4fee\u6539\uff09\u5c5e\u4e8e\u7279\u6b8a\u7684\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u3002<\/p>\n\n\n\n<p>&nbsp;\u73b0\u5728A\u96c6\u5408\u662f\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\uff0cB\u96c6\u5408\u662f\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u3002\u6bcf\u4e00\u4e2aMySQL\u5ba2\u6237\u673a\u6210\u529f\u8fde\u63a5MySQL\u670d\u52a1\u5668\u540e\uff0c\u90fd\u4f1a\u4ea7\u751f\u4e0e\u4e4b\u5bf9\u5e94\u7684\u4f1a\u8bdd\u3002\u6bcf\u4e00\u4e2aMySQL\u5ba2\u6237\u673a\u6210\u529f\u8fde\u63a5MySQL\u670d\u52a1\u5668\u540e\uff0c\u90fd\u4f1a\u4ea7\u751f\u4e0e\u4e4b\u5bf9\u5e94\u7684\u4f1a\u8bdd\u3002\u4f1a\u8bdd\u671f\u95f4\uff0cMySQL\u670d\u52a1\u5b9e\u4f8b \u4f1a\u5728MySQL\u670d\u52a1\u5668\u5185\u5b58\u4e2d\u751f\u6210\u4e0e\u8be5\u4f1a\u8bdd\u5bf9\u5e94\u7684\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\uff0c\u8fd9\u4e9b\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u7684\u521d\u59cb\u503c\u662f\u5168\u5c40\u7cfb\u7edf\u53d8 \u91cf\u503c\u7684\u590d\u5236\u3002\u5982\u4e0b\u56fe\uff1a<\/p>\n\n\n\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"\" height=\"277\" src=\"https:\/\/i-blog.csdnimg.cn\/direct\/1bdac62ee3b44d058617be3d05e827ed.png\" width=\"650\"><img loading=\"lazy\" decoding=\"async\" height=\"15\" src=\"blob:https:\/\/eve2333.top\/b6213989-062a-4d55-b011-0eeec995cd8a\" width=\"15\">\u200b\u7f16\u8f91<\/p>\n\n\n\n<p>\u5728 MySQL \u4e2d\uff0c\u5f53\u5ba2\u6237\u7aef\u53d1\u8d77\u4e00\u4e2a\u8bf7\u6c42\u5e76\u8fde\u63a5\u5230\u6570\u636e\u5e93\u65f6\uff0c\u5c31\u4f1a\u5efa\u7acb\u4e00\u4e2a\u4f1a\u8bdd\u3002\u5728\u8fd9\u4e2a\u4f1a\u8bdd\u4e2d\uff0c\u5ba2\u6237\u7aef\u53ef\u4ee5\u6267\u884c\u76f8\u5173\u7684\u64cd\u4f5c\uff0c\u6bd4\u5982\u67e5\u8be2\u6216\u4fee\u6539\u6570\u636e\u3002\u6bcf\u4e2a\u4f1a\u8bdd\u90fd\u4f1a\u6d89\u53ca\u5230\u4e00\u4e9b\u53d8\u91cf\u7684\u521d\u59cb\u5316\uff0c\u5c24\u5176\u662f\u90a3\u4e9b\u4e0e\u5168\u5c40\u53d8\u91cf\u6709\u4ea4\u96c6\u7684\u90e8\u5206\u3002\u8fd9\u4e9b\u4ea4\u96c6\u90e8\u5206\u7684\u53d8\u91cf\u521d\u59cb\u503c\u548c\u5168\u5c40\u53d8\u91cf\u662f\u4e00\u81f4\u7684\uff0c\u4f46\u6bcf\u4e2a\u4f1a\u8bdd\u8fd8\u4f1a\u6709\u4e00\u4e9b\u81ea\u5df1\u7279\u6709\u7684\u53d8\u91cf\uff0c\u968f\u7740\u4f1a\u8bdd\u7684\u521b\u5efa\uff0c\u8fd9\u4e9b\u53d8\u91cf\u4e5f\u4f1a\u88ab\u521d\u59cb\u5316\u3002<\/p>\n\n\n\n<p>\u4e0d\u540c\u5ba2\u6237\u7aef\u5efa\u7acb\u7684\u4f1a\u8bdd\u662f\u76f8\u4e92\u72ec\u7acb\u7684\u3002\u6bd4\u5982\uff0c\u5ba2\u6237\u7aef 1 \u4fee\u6539\u4e86\u5b83\u81ea\u5df1\u4f1a\u8bdd\u4e2d\u7684\u67d0\u4e2a\u53d8\u91cf\uff0c\u8fd9\u79cd\u4fee\u6539\u53ea\u4f1a\u5f71\u54cd\u5ba2\u6237\u7aef 1 \u7684\u4f1a\u8bdd\uff0c\u800c\u4e0d\u4f1a\u5f71\u54cd\u5ba2\u6237\u7aef 2 \u7684\u4f1a\u8bdd\u3002\u56e0\u4e3a\u6bcf\u4e2a\u5ba2\u6237\u7aef\u7684\u4f1a\u8bdd\u90fd\u6709\u81ea\u5df1\u72ec\u7acb\u7684\u4e00\u4efd\u53d8\u91cf\u3002\u4f46\u5982\u679c\u67d0\u4e2a\u5ba2\u6237\u7aef\u4fee\u6539\u4e86\u5168\u5c40\u53d8\u91cf\uff0c\u90a3\u4e48\u8fd9\u4e2a\u4fee\u6539\u4f1a\u5f71\u54cd\u5230\u6240\u6709\u540e\u7eed\u65b0\u5efa\u7684\u4f1a\u8bdd\uff0c\u56e0\u4e3a\u5168\u5c40\u53d8\u91cf\u662f\u5171\u4eab\u7684\u3002<\/p>\n\n\n\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u6709\u4e9b\u7cfb\u7edf\u53d8\u91cf\u662f\u5168\u5c40\u7ea7\u522b\u7684\uff0c\u4e00\u65e6\u88ab\u4fee\u6539\uff0c\u5176\u4ed6\u5ba2\u6237\u7aef\u8bbf\u95ee\u65f6\u4e5f\u4f1a\u770b\u5230\u4fee\u6539\u540e\u7684\u503c\u3002\u800c\u53e6\u4e00\u4e9b\u53d8\u91cf\u662f\u4f1a\u8bdd\u7ea7\u522b\u7684\uff0c\u4fee\u6539\u5b83\u4eec\u53ea\u4f1a\u5f71\u54cd\u5f53\u524d\u4f1a\u8bdd\uff0c\u4e0d\u4f1a\u6ce2\u53ca\u5176\u4ed6\u5ba2\u6237\u7aef\u3002\u6240\u4ee5\u5728\u64cd\u4f5c\u53d8\u91cf\u65f6\uff0c\u8981\u7279\u522b\u6ce8\u610f\u533a\u5206\u662f\u5168\u5c40\u53d8\u91cf\u8fd8\u662f\u4f1a\u8bdd\u53d8\u91cf\uff0c\u907f\u514d\u8bef\u64cd\u4f5c\u5bfc\u81f4\u95ee\u9898\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u9488\u5bf9\u4e8e\u6240\u6709\u4f1a\u8bdd\uff08\u8fde\u63a5\uff09\u6709\u6548\uff0c\u4f46 \u4e0d\u80fd\u8de8\u91cd\u542f<\/li>\n\n\n\n<li>\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u4ec5\u9488\u5bf9\u4e8e\u5f53\u524d\u4f1a\u8bdd\uff08\u8fde\u63a5\uff09\u6709\u6548\u3002\u4f1a\u8bdd\u671f\u95f4\uff0c\u5f53\u524d\u4f1a\u8bdd\u5bf9\u67d0\u4e2a\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u503c\u7684\u4fee \u6539\uff0c\u4e0d\u4f1a\u5f71\u54cd\u5176\u4ed6\u4f1a\u8bdd\u540c\u4e00\u4e2a\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\u7684\u503c\u3002.<\/li>\n\n\n\n<li>\u4f1a\u8bdd1\u5bf9\u67d0\u4e2a\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u503c\u7684\u4fee\u6539\u4f1a\u5bfc\u81f4\u4f1a\u8bdd2\u4e2d\u540c\u4e00\u4e2a\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u503c\u7684\u4fee\u6539\u3002<\/li>\n<\/ul>\n\n\n\n<p>\u5728MySQL\u4e2d\u6709\u4e9b\u7cfb\u7edf\u53d8\u91cf\u53ea\u80fd\u662f\u5168\u5c40\u7684\uff0c\u4f8b\u5982 max_connections \u7528\u4e8e\u9650\u5236\u670d\u52a1\u5668\u7684\u6700\u5927\u8fde\u63a5\u6570\uff1b\u6709\u4e9b\u7cfb \u7edf\u53d8\u91cf\u4f5c\u7528\u57df\u65e2\u53ef\u4ee5\u662f\u5168\u5c40\u53c8\u53ef\u4ee5\u662f\u4f1a\u8bdd\uff0c\u4f8b\u5982 character_set_client \u7528\u4e8e\u8bbe\u7f6e\u5ba2\u6237\u7aef\u7684\u5b57\u7b26\u96c6\uff1b\u6709\u4e9b\u7cfb \u7edf\u53d8\u91cf\u7684\u4f5c\u7528\u57df\u53ea\u80fd\u662f\u5f53\u524d\u4f1a\u8bdd\uff0c\u4f8b\u5982 pseudo_thread_id \u7528\u4e8e\u6807\u8bb0\u5f53\u524d\u4f1a\u8bdd\u7684 MySQL \u8fde\u63a5 ID&nbsp;<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#\u7b2c16\u7ae0_\u53d8\u91cf\u3001\u6d41\u7a0b\u63a7\u5236\u4e0e\u6e38\u6807\n\n#1. \u53d8\u91cf\n#1.1 \u53d8\u91cf\uff1a \u7cfb\u7edf\u53d8\u91cf\uff08\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\u3001\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\uff09  vs \u7528\u6237\u81ea\u5b9a\u4e49\u53d8\u91cf\n\n#1.2 \u67e5\u770b\u7cfb\u7edf\u53d8\u91cf\n#\u67e5\u8be2\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\nSHOW GLOBAL VARIABLES; #617\n#\u67e5\u8be2\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\nSHOW SESSION VARIABLES; #640\n\nSHOW VARIABLES; #\u9ed8\u8ba4\u67e5\u8be2\u7684\u662f\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\n\n#\u67e5\u8be2\u90e8\u5206\u7cfb\u7edf\u53d8\u91cf\n\nSHOW GLOBAL VARIABLES LIKE 'admin_%';\n\nSHOW VARIABLES LIKE 'character_%';\n\n#1.3 \u67e5\u770b\u6307\u5b9a\u7cfb\u7edf\u53d8\u91cf\n\nSELECT @@global.max_connections;\nSELECT @@global.character_set_client;\n\n#\u9519\u8bef\uff1a\nSELECT @@global.pseudo_thread_id;\n\n\u5728MySQL\u4e2d\u6709\u4e9b\u7cfb\u7edf\u53d8\u91cf\u53ea\u80fd\u662f\u5168\u5c40\u7684\uff0c\u4f8b\u5982max_connections\u7528\u4e8e\u9650\u5236\u670d\u52a1\u5668\u7684\u6700\u5927\u8fde\u63a5\u6570\uff1b\n\u6709\u4e9b\u7cfb\u7edf\u53d8\u91cf\u4f5c\u7528\u57df\u65e2\u53ef\u4ee5\u662f\u5168\u5c40\u53c8\u53ef\u4ee5\u662f\u4f1a\u8bdd\uff0c\u4f8b\u5982character_set_client\u7528\u4e8e\u8bbe\u7f6e\u5ba2\u6237\u7aef\u7684\u5b57\u7b26\u96c6\uff1b\n\u6709\u4e9b\u7cfb\u7edf\u53d8\u91cf\u7684\u4f5c\u7528\u57df\u53ea\u80fd\u662f\u5f53\u524d\u4f1a\u8bdd\uff0c\u4f8b\u5982pseudo_thread_id\u7528\u4e8e\u6807\u8bb0\u5f53\u524d\u4f1a\u8bdd\u7684MySQL\u8fde\u63a5ID\u3002\n\n#\u9519\u8bef\uff1a\nSELECT @@session.max_connections;\n\nSELECT @@session.character_set_client;\n\nSELECT @@session.pseudo_thread_id;\n\nSELECT @@character_set_client; #\u5148\u67e5\u8be2\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\uff0c\u518d\u67e5\u8be2\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\n\n#1.4 \u4fee\u6539\u7cfb\u7edf\u53d8\u91cf\u7684\u503c\n#\u5168\u5c40\u7cfb\u7edf\u53d8\u91cf\uff1a\n#\u65b9\u5f0f1\uff1a\nSET @@global.max_connections = 161;\n#\u65b9\u5f0f2\uff1a\nSET GLOBAL max_connections = 171;\n\n#\u9488\u5bf9\u4e8e\u5f53\u524d\u7684\u6570\u636e\u5e93\u5b9e\u4f8b\u662f\u6709\u6548\u7684\uff0c\u4e00\u65e6\u91cd\u542fmysql\u670d\u52a1\uff0c\u5c31\u5931\u6548\u4e86\u3002\n\n\n#\u4f1a\u8bdd\u7cfb\u7edf\u53d8\u91cf\uff1a\n#\u65b9\u5f0f1\uff1a\nSET @@session.character_set_client = 'gbk';\n#\u65b9\u5f0f2\uff1a\nSET SESSION character_set_client = 'gbk';\n\n#\u9488\u5bf9\u4e8e\u5f53\u524d\u4f1a\u8bdd\u662f\u6709\u6548\u7684\uff0c\u4e00\u65e6\u7ed3\u675f\u4f1a\u8bdd\uff0c\u91cd\u65b0\u5efa\u7acb\u8d77\u65b0\u7684\u4f1a\u8bdd\uff0c\u5c31\u5931\u6548\u4e86\u3002\n\n\n<\/code><\/pre>\n\n\n\n<p><img loading=\"lazy\" decoding=\"async\" height=\"15\" src=\"blob:https:\/\/eve2333.top\/84d5de5e-4a9e-4b02-b290-6216726a2931\" width=\"15\"><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1.2 \u7528\u6237\u53d8\u91cf&nbsp;&nbsp;<\/h3>\n\n\n\n<p>\u7528\u6237\u53d8\u91cf\u662f\u7528\u6237\u81ea\u5df1\u5b9a\u4e49\u7684\uff0c\u4f5c\u4e3a MySQL \u7f16\u7801\u89c4\u8303\uff0cMySQL \u4e2d\u7684\u7528\u6237\u53d8\u91cf\u4ee5 \u8303\u56f4\u4e0d\u540c\uff0c\u53c8\u5206\u4e3a \u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\u548c \u5c40\u90e8\u53d8\u91cf\u3002<\/p>\n\n\n\n<p>\u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\uff1a\u4f5c\u7528\u57df\u548c\u4f1a\u8bdd\u53d8\u91cf\u4e00\u6837\uff0c\u53ea\u5bf9 \u4e00\u4e2a\u201c@\u201d \u5f00\u5934\u3002\u6839\u636e\u4f5c\u7528 \u5f53\u524d\u8fde\u63a5\u4f1a\u8bdd\u6709\u6548\u3002<br>\u5c40 \u90e8\u53d8\u91cf\uff1a\u53ea\u5728 BEGIN \u548c END \u8bed\u53e5\u5757\u4e2d\u6709\u6548\u3002\u5c40\u90e8\u53d8\u91cf\u53ea\u80fd\u5728 \u5b58\u50a8\u8fc7\u7a0b\u548c\u51fd\u6570\u4e2d\u4f7f\u7528\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#1.5 \u7528\u6237\u53d8\u91cf\n\/*\n\u2460 \u7528\u6237\u53d8\u91cf \uff1a \u4f1a\u8bdd\u7528\u6237\u53d8\u91cf vs \u5c40\u90e8\u53d8\u91cf\n\n\u2461 \u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\uff1a\u4f7f\u7528\"@\"\u5f00\u5934\uff0c\u4f5c\u7528\u57df\u4e3a\u5f53\u524d\u4f1a\u8bdd\u3002\n\n\u2462 \u5c40\u90e8\u53d8\u91cf\uff1a\u53ea\u80fd\u4f7f\u7528\u5728\u5b58\u50a8\u8fc7\u7a0b\u548c\u5b58\u50a8\u51fd\u6570\u4e2d\u7684\u3002\n\n*\/\n\n#1.6 \u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\n\/*\n\u2460 \u53d8\u91cf\u7684\u58f0\u660e\u548c\u8d4b\u503c\uff1a\n#\u65b9\u5f0f1\uff1a\u201c=\u201d\u6216\u201c:=\u201d\nSET @\u7528\u6237\u53d8\u91cf = \u503c;\nSET @\u7528\u6237\u53d8\u91cf := \u503c;\n\n#\u65b9\u5f0f2\uff1a\u201c:=\u201d \u6216 INTO\u5173\u952e\u5b57\nSELECT @\u7528\u6237\u53d8\u91cf := \u8868\u8fbe\u5f0f &#91;FROM \u7b49\u5b50\u53e5];\nSELECT \u8868\u8fbe\u5f0f INTO @\u7528\u6237\u53d8\u91cf  &#91;FROM \u7b49\u5b50\u53e5];\n\n\u2461 \u4f7f\u7528\nSELECT @\u53d8\u91cf\u540d\n\n*\/\n#\u51c6\u5907\u5de5\u4f5c\nCREATE DATABASE dbtest16;\n\nUSE dbtest16;\n\nCREATE TABLE employees\nAS\nSELECT * FROM atguigudb.`employees`;\n\nCREATE TABLE departments\nAS\nSELECT * FROM atguigudb.`departments`;\n\nSELECT * FROM employees;\nSELECT * FROM departments;\n\n#\u6d4b\u8bd5\uff1a\n#\u65b9\u5f0f1\uff1a\nSET @m1 = 1;\nSET @m2 := 2;\nSET @sum := @m1 + @m2;\n\nSELECT @sum;\n\n#\u65b9\u5f0f2\uff1a\nSELECT @count := COUNT(*) FROM employees;\n\nSELECT @count;\n\nSELECT AVG(salary) INTO @avg_sal FROM employees;\n\nSELECT @avg_sal;\n\n#1.7 \u5c40\u90e8\u53d8\u91cf\n\/*\n1\u3001\u5c40\u90e8\u53d8\u91cf\u5fc5\u987b\u6ee1\u8db3\uff1a\n\u2460 \u4f7f\u7528DECLARE\u58f0\u660e \n\u2461 \u58f0\u660e\u5e76\u4f7f\u7528\u5728BEGIN ... END \u4e2d \uff08\u4f7f\u7528\u5728\u5b58\u50a8\u8fc7\u7a0b\u3001\u51fd\u6570\u4e2d\uff09\n\u2462 DECLARE\u7684\u65b9\u5f0f\u58f0\u660e\u7684\u5c40\u90e8\u53d8\u91cf\u5fc5\u987b\u58f0\u660e\u5728BEGIN\u4e2d\u7684\u9996\u884c\u7684\u4f4d\u7f6e\u3002\n\n2\u3001\u58f0\u660e\u683c\u5f0f\uff1a\nDECLARE \u53d8\u91cf\u540d \u7c7b\u578b &#91;default \u503c];  # \u5982\u679c\u6ca1\u6709DEFAULT\u5b50\u53e5\uff0c\u521d\u59cb\u503c\u4e3aNULL\n\n3\u3001\u8d4b\u503c\uff1a\n\u65b9\u5f0f1\uff1a\nSET \u53d8\u91cf\u540d=\u503c;\nSET \u53d8\u91cf\u540d:=\u503c;\n\n\u65b9\u5f0f2\uff1a\nSELECT \u5b57\u6bb5\u540d\u6216\u8868\u8fbe\u5f0f INTO \u53d8\u91cf\u540d FROM \u8868;\n\n4\u3001\u4f7f\u7528\nSELECT \u5c40\u90e8\u53d8\u91cf\u540d;\n*\/\n\n#\u4e3e\u4f8b\uff1a\nDELIMITER \/\/\n\nCREATE PROCEDURE test_var()\n\nBEGIN\n\t#1\u3001\u58f0\u660e\u5c40\u90e8\u53d8\u91cf\n\tDECLARE a INT DEFAULT 0;\n\tDECLARE b INT ;\n\t#DECLARE a,b INT DEFAULT 0;\n\tDECLARE emp_name VARCHAR(25);\n\t\n\t#2\u3001\u8d4b\u503c\n\tSET a = 1;\n\tSET b := 2;\n\t\n\tSELECT last_name INTO emp_name FROM employees WHERE employee_id = 101;\n\t\n\t#3\u3001\u4f7f\u7528\n\tSELECT a,b,emp_name;\t\nEND \/\/\n\nDELIMITER ;\n\n#\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\nCALL test_var();\n\n#\u4e3e\u4f8b1\uff1a\u58f0\u660e\u5c40\u90e8\u53d8\u91cf\uff0c\u5e76\u5206\u522b\u8d4b\u503c\u4e3aemployees\u8868\u4e2demployee_id\u4e3a102\u7684last_name\u548csalary\n\nDELIMITER \/\/\n\nCREATE PROCEDURE test_pro()\nBEGIN\n\t#\u58f0\u660e\n\tDECLARE emp_name VARCHAR(25);\n\tDECLARE sal DOUBLE(10,2) DEFAULT 0.0;\n\t#\u8d4b\u503c\n\tSELECT last_name,salary INTO emp_name,sal\n\tFROM employees\n\tWHERE employee_id = 102;\n\t#\u4f7f\u7528\n\tSELECT emp_name,sal;\n\t\nEND \/\/\n\nDELIMITER ;\n\n#\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\n\nCALL test_pro();\n\nSELECT last_name,salary FROM employees\nWHERE employee_id = 102;\n\n#\u4e3e\u4f8b2\uff1a\u58f0\u660e\u4e24\u4e2a\u53d8\u91cf\uff0c\u6c42\u548c\u5e76\u6253\u5370 \uff08\u5206\u522b\u4f7f\u7528\u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\u3001\u5c40\u90e8\u53d8\u91cf\u7684\u65b9\u5f0f\u5b9e\u73b0\uff09\n\n#\u65b9\u5f0f1\uff1a\u4f7f\u7528\u4f1a\u8bdd\u7528\u6237\u53d8\u91cf\nSET @v1 = 10;\nSET @v2 := 20;\nSET @result := @v1 + @v2;\n\n#\u67e5\u770b\nSELECT @result;\n\n#\u65b9\u5f0f2\uff1a\u4f7f\u7528\u5c40\u90e8\u53d8\u91cf\nDELIMITER \/\/\n\nCREATE PROCEDURE add_value()\nBEGIN\n\t#\u58f0\u660e\n\tDECLARE value1,value2,sum_val INT;\n\t\n\t#\u8d4b\u503c\n\tSET value1 = 10;\n\tSET value2 := 100;\n\t\n\tSET sum_val = value1 + value2;\n\t#\u4f7f\u7528\n\tSELECT sum_val;\nEND \/\/\n\nDELIMITER ;\n\n#\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\nCALL add_value();\n\n#\u4e3e\u4f8b3\uff1a\u521b\u5efa\u5b58\u50a8\u8fc7\u7a0b\u201cdifferent_salary\u201d\u67e5\u8be2\u67d0\u5458\u5de5\u548c\u4ed6\u9886\u5bfc\u7684\u85aa\u8d44\u5dee\u8ddd\uff0c\u5e76\u7528IN\u53c2\u6570emp_id\u63a5\u6536\u5458\u5de5id\uff0c\n#\u7528OUT\u53c2\u6570dif_salary\u8f93\u51fa\u85aa\u8d44\u5dee\u8ddd\u7ed3\u679c\u3002\n\nDELIMITER \/\/\n\nCREATE PROCEDURE different_salary(IN emp_id INT,OUT dif_salary DOUBLE)\nBEGIN\n\t#\u5206\u6790\uff1a\u67e5\u8be2\u51faemp_id\u5458\u5de5\u7684\u5de5\u8d44;\u67e5\u8be2\u51faemp_id\u5458\u5de5\u7684\u7ba1\u7406\u8005\u7684id;\u67e5\u8be2\u7ba1\u7406\u8005id\u7684\u5de5\u8d44;\u8ba1\u7b97\u4e24\u4e2a\u5de5\u8d44\u7684\u5dee\u503c\n\t\n\t#\u58f0\u660e\u53d8\u91cf\n\tDECLARE emp_sal DOUBLE DEFAULT 0.0; #\u8bb0\u5f55\u5458\u5de5\u7684\u5de5\u8d44\n\tDECLARE mgr_sal DOUBLE DEFAULT 0.0; #\u8bb0\u5f55\u7ba1\u7406\u8005\u7684\u5de5\u8d44\n\t\n\tDECLARE mgr_id INT DEFAULT 0; #\u8bb0\u5f55\u7ba1\u7406\u8005\u7684id\n\t\n\t\n\t#\u8d4b\u503c\n\tSELECT salary INTO emp_sal FROM employees WHERE employee_id = emp_id;\n\t\n\tSELECT manager_id INTO mgr_id FROM employees WHERE employee_id = emp_id;\n\tSELECT salary INTO mgr_sal FROM employees WHERE employee_id = mgr_id;\n\t\n\tSET dif_salary = mgr_sal - emp_sal;\n\nEND \/\/\nDELIMITER ;\n\n#\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\nSET @emp_id := 103;\nSET @dif_sal := 0;\nCALL different_salary(@emp_id,@dif_sal);\n\nSELECT @dif_sal;\n\n\nSELECT * FROM employees;<\/code><\/pre>\n\n\n\n<p><img loading=\"lazy\" decoding=\"async\" height=\"15\" src=\"blob:https:\/\/eve2333.top\/6fd38417-1ca4-448e-bf53-60a8cc6e1017\" width=\"15\"> \u200b<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u200b &nbsp;\u7b2c16\u7ae0_\u53d8\u91cf\u3001\u6d41\u7a0b\u63a7\u5236\u4e0e\u6e38\u6807 1.1 \u7cfb\u7edf\u53d8\u91cf 1.1.1 \u7cfb\u7edf\u53d8\u91cf\u5206\u7c7b &nbsp;\u53d8\u91cf\u7531\u7cfb\u7edf\u5b9a\u4e49\uff0c\u4e0d\u662f\u7528\u6237\u5b9a &#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[2],"tags":[16],"class_list":["post-870","post","type-post","status-publish","format-standard","hentry","category-2","tag-sql"],"_links":{"self":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=870"}],"version-history":[{"count":2,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/870\/revisions"}],"predecessor-version":[{"id":875,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/870\/revisions\/875"}],"wp:attachment":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=870"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=870"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}