{"id":75834,"date":"2024-10-16T01:37:17","date_gmt":"2024-10-15T17:37:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/75834\/"},"modified":"2024-10-16T01:37:17","modified_gmt":"2024-10-15T17:37:17","slug":"mysql-%e5%b8%b8%e7%94%a8%e6%8a%80%e5%b7%a7%e5%a4%a7%e5%8c%af%e7%b8%bd","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/75834\/","title":{"rendered":"MySQL \u5e38\u7528\u6280\u5de7\u5927\u532f\u7e3d"},"content":{"rendered":"<h1 id=\"mysql-%e5%b8%b8%e7%94%a8%e6%8a%80%e5%b7%a7%e5%a4%a7%e5%8c%af%e7%b8%bd-uMrfuIJgZz\">MySQL \u5e38\u7528\u6280\u5de7\u5927\u532f\u7e3d<\/h1>\n<p>MySQL \u662f\u4e00\u7a2e\u6d41\u884c\u7684\u958b\u6e90\u95dc\u806f\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u5404\u7a2e\u7db2\u7ad9\u548c\u61c9\u7528\u7a0b\u5e8f\u4e2d\u3002\u7121\u8ad6\u662f\u5c0f\u578b\u9805\u76ee\u9084\u662f\u5927\u578b\u4f01\u696d\u7d1a\u61c9\u7528\uff0c\u638c\u63e1\u4e00\u4e9b MySQL \u7684\u5e38\u7528\u6280\u5de7\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6027\u80fd\u548c\u6548\u7387\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u4e00\u4e9b\u5be6\u7528\u7684 MySQL \u6280\u5de7\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u597d\u5730\u7ba1\u7406\u548c\u512a\u5316\u6578\u64da\u5eab\u3002<\/p>\n<h2 id=\"1-%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95%e6%8f%90%e9%ab%98%e6%9f%a5%e8%a9%a2%e6%80%a7%e8%83%bd-uMrfuIJgZz\">1. \u4f7f\u7528\u7d22\u5f15\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd<\/h2>\n<p>\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u7684\u95dc\u9375\u3002\u901a\u904e\u5728\u8868\u7684\u67d0\u4e9b\u5217\u4e0a\u5275\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u52a0\u901f\u67e5\u8a62\u64cd\u4f5c\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u7d22\u5f15\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>CREATE INDEX index_name ON table_name (column_name);<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5c0d\u65bc\u4e00\u500b\u7528\u6236\u8868\uff0c\u5982\u679c\u7d93\u5e38\u6839\u64da\u7528\u6236\u540d\u67e5\u8a62\uff0c\u53ef\u4ee5\u9019\u6a23\u5275\u5efa\u7d22\u5f15\uff1a<\/p>\n<pre><code>CREATE INDEX idx_username ON users (username);<\/code><\/pre>\n<h2 id=\"2-%e4%bd%bf%e7%94%a8-join-%e9%80%b2%e8%a1%8c%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2-uMrfuIJgZz\">2. \u4f7f\u7528 JOIN \u9032\u884c\u591a\u8868\u67e5\u8a62<\/h2>\n<p>\u5728 MySQL \u4e2d\uff0cJOIN \u64cd\u4f5c\u53ef\u4ee5\u8b93\u4f60\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002\u5e38\u898b\u7684 JOIN \u985e\u578b\u5305\u62ec INNER JOIN\u3001LEFT JOIN \u548c RIGHT JOIN\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 INNER JOIN \u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT users.username, orders.order_date \nFROM users \nINNER JOIN orders ON users.id = orders.user_id;<\/code><\/pre>\n<p>\u9019\u6a23\u53ef\u4ee5\u7372\u53d6\u6bcf\u500b\u7528\u6236\u53ca\u5176\u8a02\u55ae\u65e5\u671f\u7684\u4fe1\u606f\u3002<\/p>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8-group-by-%e5%92%8c%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8-uMrfuIJgZz\">3. \u4f7f\u7528 GROUP BY \u548c\u805a\u5408\u51fd\u6578<\/h2>\n<p>\u7576\u9700\u8981\u5c0d\u6578\u64da\u9032\u884c\u5206\u7d44\u548c\u8a08\u7b97\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528 GROUP BY \u548c\u805a\u5408\u51fd\u6578\uff08\u5982 COUNT\u3001SUM\u3001AVG \u7b49\uff09\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u8a08\u7b97\u6bcf\u500b\u7528\u6236\u7684\u8a02\u55ae\u6578\u91cf\uff1a<\/p>\n<pre><code>SELECT user_id, COUNT(*) AS order_count \nFROM orders \nGROUP BY user_id;<\/code><\/pre>\n<h2 id=\"4-%e4%bd%bf%e7%94%a8%e4%ba%8b%e5%8b%99%e7%a2%ba%e4%bf%9d%e6%95%b8%e6%93%9a%e4%b8%80%e8%87%b4%e6%80%a7-uMrfuIJgZz\">4. \u4f7f\u7528\u4e8b\u52d9\u78ba\u4fdd\u6578\u64da\u4e00\u81f4\u6027<\/h2>\n<p>\u4e8b\u52d9\u662f\u4e00\u7d44\u64cd\u4f5c\u7684\u96c6\u5408\uff0c\u9019\u4e9b\u64cd\u4f5c\u8981\u9ebc\u5168\u90e8\u6210\u529f\uff0c\u8981\u9ebc\u5168\u90e8\u5931\u6557\u3002\u4f7f\u7528\u4e8b\u52d9\u53ef\u4ee5\u78ba\u4fdd\u6578\u64da\u7684\u4e00\u81f4\u6027\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528\u4e8b\u52d9\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>START TRANSACTION; \n-- \u57f7\u884c\u591a\u500b SQL \u64cd\u4f5c \nCOMMIT; -- \u63d0\u4ea4\u4e8b\u52d9<\/code><\/pre>\n<p>\u5982\u679c\u5728\u57f7\u884c\u904e\u7a0b\u4e2d\u51fa\u73fe\u932f\u8aa4\uff0c\u53ef\u4ee5\u4f7f\u7528 ROLLBACK \u4f86\u64a4\u92b7\u6240\u6709\u64cd\u4f5c\u3002<\/p>\n<h2 id=\"5-%e4%bd%bf%e7%94%a8-explain-%e5%88%86%e6%9e%90%e6%9f%a5%e8%a9%a2%e6%80%a7%e8%83%bd-uMrfuIJgZz\">5. \u4f7f\u7528 EXPLAIN \u5206\u6790\u67e5\u8a62\u6027\u80fd<\/h2>\n<p>EXPLAIN \u8a9e\u53e5\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u5206\u6790\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\uff0c\u5f9e\u800c\u627e\u51fa\u6027\u80fd\u74f6\u9838\u3002\u4f7f\u7528\u65b9\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>EXPLAIN SELECT * FROM users WHERE username = 'example';<\/code><\/pre>\n<p>\u9019\u5c07\u986f\u793a MySQL \u5982\u4f55\u57f7\u884c\u8a72\u67e5\u8a62\uff0c\u5305\u62ec\u4f7f\u7528\u7684\u7d22\u5f15\u548c\u9810\u8a08\u7684\u884c\u6578\u3002<\/p>\n<h2 id=\"6-%e5%ae%9a%e6%9c%9f%e5%82%99%e4%bb%bd%e6%95%b8%e6%93%9a-uMrfuIJgZz\">6. \u5b9a\u671f\u5099\u4efd\u6578\u64da<\/h2>\n<p>\u6578\u64da\u5099\u4efd\u662f\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\u4e0d\u53ef\u6216\u7f3a\u7684\u4e00\u90e8\u5206\u3002\u53ef\u4ee5\u4f7f\u7528 mysqldump \u5de5\u5177\u9032\u884c\u5099\u4efd\uff0c\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>mysqldump -u username -p database_name &gt; backup.sql<\/code><\/pre>\n<p>\u9019\u6a23\u53ef\u4ee5\u5c07\u6307\u5b9a\u6578\u64da\u5eab\u7684\u6578\u64da\u5c0e\u51fa\u5230\u4e00\u500b SQL \u6587\u4ef6\u4e2d\uff0c\u65b9\u4fbf\u65e5\u5f8c\u6062\u5fa9\u3002<\/p>\n<h2 id=\"7-%e5%84%aa%e5%8c%96%e6%9f%a5%e8%a9%a2%e8%aa%9e%e5%8f%a5-uMrfuIJgZz\">7. \u512a\u5316\u67e5\u8a62\u8a9e\u53e5<\/h2>\n<p>\u512a\u5316\u67e5\u8a62\u8a9e\u53e5\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u6027\u80fd\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u512a\u5316\u5efa\u8b70\uff1a<\/p>\n<ul>\n<li>\u907f\u514d\u4f7f\u7528 SELECT *\uff0c\u53ea\u9078\u64c7\u9700\u8981\u7684\u5217\u3002<\/li>\n<li>\u4f7f\u7528 WHERE \u5b50\u53e5\u904e\u6ffe\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u3002<\/li>\n<li>\u907f\u514d\u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528\u51fd\u6578\uff0c\u9019\u6a23\u6703\u5c0e\u81f4\u5168\u8868\u6383\u63cf\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-uMrfuIJgZz\">\u7e3d\u7d50<\/h2>\n<p>\u638c\u63e1 MySQL \u7684\u5e38\u7528\u6280\u5de7\u4e0d\u50c5\u80fd\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u9084\u80fd\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u9ad8\u6548\u5730\u7ba1\u7406\u6578\u64da\u3002\u7121\u8ad6\u662f\u4f7f\u7528\u7d22\u5f15\u3001JOIN \u64cd\u4f5c\uff0c\u9084\u662f\u4e8b\u52d9\u7ba1\u7406\u548c\u67e5\u8a62\u512a\u5316\uff0c\u9019\u4e9b\u6280\u5de7\u90fd\u80fd\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u767c\u63ee\u91cd\u8981\u4f5c\u7528\u3002\u5982\u679c\u60a8\u9700\u8981\u66f4\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u53ef\u4ee5\u8003\u616e\u4f7f\u7528 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u670d\u52d9\uff0c\u9019\u5c07\u70ba\u60a8\u7684\u61c9\u7528\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22 MySQL \u5e38\u7528\u6280\u5de7\uff0c\u63d0\u5347\u6578\u64da\u5eab\u7ba1\u7406\u6548\u7387\uff0c\u512a\u5316\u67e5\u8a62\u6027\u80fd\uff0c\u638c\u63e1\u5be6\u7528\u547d\u4ee4\u8207\u6700\u4f73\u5be6\u8e10\uff0c\u52a9\u4f60\u6210\u70ba MySQL \u5927\u5e2b\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-75834","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75834","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=75834"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75834\/revisions"}],"predecessor-version":[{"id":75835,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/75834\/revisions\/75835"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=75834"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=75834"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=75834"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}