{"id":170,"date":"2018-10-13T17:58:05","date_gmt":"2018-10-13T09:58:05","guid":{"rendered":"https:\/\/wp.dj47.top\/?p=170"},"modified":"2021-10-20T16:19:02","modified_gmt":"2021-10-20T08:19:02","slug":"mysql%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e7%9a%84%e6%9c%80%e4%bd%b321%e6%9d%a1%e7%bb%8f%e9%aa%8c","status":"publish","type":"post","link":"https:\/\/www.djlog.cn\/?p=170","title":{"rendered":"MySQL\u6027\u80fd\u4f18\u5316\u7684\u6700\u4f7321\u6761\u7ecf\u9a8c"},"content":{"rendered":"

\u4eca\u5929\uff0c\u6570\u636e\u5e93\u7684\u64cd\u4f5c\u8d8a\u6765\u8d8a\u6210\u4e3a\u6574\u4e2a\u5e94\u7528\u7684\u6027\u80fd\u74f6\u9888\u4e86\uff0c\u8fd9\u70b9\u5bf9\u4e8eWeb\u5e94\u7528\u5c24\u5176\u660e\u663e\u3002\u5173\u4e8e\u6570\u636e\u5e93\u7684\u6027\u80fd\uff0c\u8fd9\u5e76\u4e0d\u53ea\u662fDBA\u624d\u9700\u8981\u62c5\u5fc3\u7684\u4e8b\uff0c\u800c\u8fd9\u66f4\u662f\u6211\u4eec\u7a0b\u5e8f\u5458\u9700\u8981\u53bb\u5173\u6ce8\u7684\u4e8b\u60c5\u3002\u5f53\u6211\u4eec\u53bb\u8bbe\u8ba1\u6570\u636e\u5e93\u8868\u7ed3\u6784\uff0c\u5bf9\u64cd\u4f5c\u6570\u636e\u5e93\u65f6\uff08\u5c24\u5176\u662f\u67e5\u8868\u65f6\u7684SQL\u8bed\u53e5\uff09\uff0c\u6211\u4eec\u90fd\u9700\u8981\u6ce8\u610f\u6570\u636e\u64cd\u4f5c\u7684\u6027\u80fd\u3002\u8fd9\u91cc\uff0c\u6211\u4eec\u4e0d\u4f1a\u8bb2\u8fc7\u591a\u7684SQL\u8bed\u53e5\u7684\u4f18\u5316\uff0c\u800c\u53ea\u662f\u9488\u5bf9MySQL\u8fd9\u4e00Web\u5e94\u7528\u6700\u591a\u7684\u6570\u636e\u5e93\u3002\u5e0c\u671b\u4e0b\u9762\u7684\u8fd9\u4e9b\u4f18\u5316\u6280\u5de7\u5bf9\u4f60\u6709\u7528\u3002<\/p>\n

1. \u4e3a\u67e5\u8be2\u7f13\u5b58\u4f18\u5316\u4f60\u7684\u67e5\u8be2<\/h4>\n

\u5927\u591a\u6570\u7684MySQL\u670d\u52a1\u5668\u90fd\u5f00\u542f\u4e86\u67e5\u8be2\u7f13\u5b58\u3002\u8fd9\u662f\u63d0\u9ad8\u6027\u6700\u6709\u6548\u7684\u65b9\u6cd5\u4e4b\u4e00\uff0c\u800c\u4e14\u8fd9\u662f\u88abMySQL\u7684\u6570\u636e\u5e93\u5f15\u64ce\u5904\u7406\u7684\u3002\u5f53\u6709\u5f88\u591a\u76f8\u540c\u7684\u67e5\u8be2\u88ab\u6267\u884c\u4e86\u591a\u6b21\u7684\u65f6\u5019\uff0c\u8fd9\u4e9b\u67e5\u8be2\u7ed3\u679c\u4f1a\u88ab\u653e\u5230\u4e00\u4e2a\u7f13\u5b58\u4e2d\uff0c\u8fd9\u6837\uff0c\u540e\u7eed\u7684\u76f8\u540c\u7684\u67e5\u8be2\u5c31\u4e0d\u7528\u64cd\u4f5c\u8868\u800c\u76f4\u63a5\u8bbf\u95ee\u7f13\u5b58\u7ed3\u679c\u4e86\u3002<\/p>\n

\u8fd9\u91cc\u6700\u4e3b\u8981\u7684\u95ee\u9898\u662f\uff0c\u5bf9\u4e8e\u7a0b\u5e8f\u5458\u6765\u8bf4\uff0c\u8fd9\u4e2a\u4e8b\u60c5\u662f\u5f88\u5bb9\u6613\u88ab\u5ffd\u7565\u7684\u3002\u56e0\u4e3a\uff0c\u6211\u4eec\u67d0\u4e9b\u67e5\u8be2\u8bed\u53e5\u4f1a\u8ba9MySQL\u4e0d\u4f7f\u7528\u7f13\u5b58\u3002\u8bf7\u770b\u4e0b\u9762\u7684\u793a\u4f8b\uff1a<\/p>\n

\/\/ \u67e5\u8be2\u7f13\u5b58\u4e0d\u5f00\u542f\r\n$r = mysql_query(\"SELECT username FROM user WHERE signup_date >= CURDATE()\");\r\n \r\n\/\/ \u5f00\u542f\u67e5\u8be2\u7f13\u5b58\r\n$today = date(\"Y-m-d\");\r\n$r = mysql_query(\"SELECT username FROM user WHERE signup_date >= '$today'\");<\/code><\/pre>\n
\u4e0a\u9762\u4e24\u6761SQL\u8bed\u53e5\u7684\u5dee\u522b\u5c31\u662f CURDATE() \uff0cMySQL\u7684\u67e5\u8be2\u7f13\u5b58\u5bf9\u8fd9\u4e2a\u51fd\u6570\u4e0d\u8d77\u4f5c\u7528\u3002\u6240\u4ee5\uff0c\u50cf NOW() \u548c RAND() \u6216\u662f\u5176\u5b83\u7684\u8bf8\u5982\u6b64\u7c7b\u7684SQL\u51fd\u6570\u90fd\u4e0d\u4f1a\u5f00\u542f\u67e5\u8be2\u7f13\u5b58\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u51fd\u6570\u7684\u8fd4\u56de\u662f\u4f1a\u4e0d\u5b9a\u7684\u6613\u53d8\u7684\u3002\u6240\u4ee5\uff0c\u4f60\u6240\u9700\u8981\u7684\u5c31\u662f\u7528\u4e00\u4e2a\u53d8\u91cf\u6765\u4ee3\u66ffMySQL\u7684\u51fd\u6570\uff0c\u4ece\u800c\u5f00\u542f\u7f13\u5b58\u3002<\/p>\n
2. EXPLAIN \u4f60\u7684 SELECT \u67e5\u8be2<\/h4>\n
\u4f7f\u7528\u00a0EXPLAIN<\/a>\u00a0\u5173\u952e\u5b57\u53ef\u4ee5\u8ba9\u4f60\u77e5\u9053MySQL\u662f\u5982\u4f55\u5904\u7406\u4f60\u7684SQL\u8bed\u53e5\u7684\u3002\u8fd9\u53ef\u4ee5\u5e2e\u4f60\u5206\u6790\u4f60\u7684\u67e5\u8be2\u8bed\u53e5\u6216\u662f\u8868\u7ed3\u6784\u7684\u6027\u80fd\u74f6\u9888\u3002<\/p>\n
EXPLAIN \u7684\u67e5\u8be2\u7ed3\u679c\u8fd8\u4f1a\u544a\u8bc9\u4f60\u4f60\u7684\u7d22\u5f15\u4e3b\u952e\u88ab\u5982\u4f55\u5229\u7528\u7684\uff0c\u4f60\u7684\u6570\u636e\u8868\u662f\u5982\u4f55\u88ab\u641c\u7d22\u548c\u6392\u5e8f\u7684\u2026\u2026\u7b49\u7b49\uff0c\u7b49\u7b49\u3002<\/p>\n
\u6311\u4e00\u4e2a\u4f60\u7684SELECT\u8bed\u53e5\uff08\u63a8\u8350\u6311\u9009\u90a3\u4e2a\u6700\u590d\u6742\u7684\uff0c\u6709\u591a\u8868\u8054\u63a5\u7684\uff09\uff0c\u628a\u5173\u952e\u5b57EXPLAIN\u52a0\u5230\u524d\u9762\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528phpmyadmin\u6765\u505a\u8fd9\u4e2a\u4e8b\u3002\u7136\u540e\uff0c\u4f60\u4f1a\u770b\u5230\u4e00\u5f20\u8868\u683c\u3002\u4e0b\u9762\u7684\u8fd9\u4e2a\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u5fd8\u8bb0\u52a0\u4e0a\u4e86group_id\u7d22\u5f15\uff0c\u5e76\u4e14\u6709\u8868\u8054\u63a5\uff1a<\/p>\n
\"\"<\/div><\/div>\n
\u5f53\u6211\u4eec\u4e3a group_id \u5b57\u6bb5\u52a0\u4e0a\u7d22\u5f15\u540e\uff1a<\/p>\n
\"\"<\/div><\/div>\n
\u6211\u4eec\u53ef\u4ee5\u770b\u5230\uff0c\u524d\u4e00\u4e2a\u7ed3\u679c\u663e\u793a\u641c\u7d22\u4e86 7883 \u884c\uff0c\u800c\u540e\u4e00\u4e2a\u53ea\u662f\u641c\u7d22\u4e86\u4e24\u4e2a\u8868\u7684 9 \u548c 16 \u884c\u3002\u67e5\u770brows\u5217\u53ef\u4ee5\u8ba9\u6211\u4eec\u627e\u5230\u6f5c\u5728\u7684\u6027\u80fd\u95ee\u9898\u3002<\/p>\n
3. \u5f53\u53ea\u8981\u4e00\u884c\u6570\u636e\u65f6\u4f7f\u7528 LIMIT 1<\/h4>\n
\u5f53\u4f60\u67e5\u8be2\u8868\u7684\u6709\u4e9b\u65f6\u5019\uff0c\u4f60\u5df2\u7ecf\u77e5\u9053\u7ed3\u679c\u53ea\u4f1a\u6709\u4e00\u6761\u7ed3\u679c\uff0c\u4f46\u56e0\u4e3a\u4f60\u53ef\u80fd\u9700\u8981\u53bbfetch\u6e38\u6807\uff0c\u6216\u662f\u4f60\u4e5f\u8bb8\u4f1a\u53bb\u68c0\u67e5\u8fd4\u56de\u7684\u8bb0\u5f55\u6570\u3002<\/p>\n
\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u52a0\u4e0a LIMIT 1 \u53ef\u4ee5\u589e\u52a0\u6027\u80fd\u3002\u8fd9\u6837\u4e00\u6837\uff0cMySQL\u6570\u636e\u5e93\u5f15\u64ce\u4f1a\u5728\u627e\u5230\u4e00\u6761\u6570\u636e\u540e\u505c\u6b62\u641c\u7d22\uff0c\u800c\u4e0d\u662f\u7ee7\u7eed\u5f80\u540e\u67e5\u5c11\u4e0b\u4e00\u6761\u7b26\u5408\u8bb0\u5f55\u7684\u6570\u636e\u3002<\/p>\n
\u4e0b\u9762\u7684\u793a\u4f8b\uff0c\u53ea\u662f\u4e3a\u4e86\u627e\u4e00\u4e0b\u662f\u5426\u6709\u201c\u4e2d\u56fd\u201d\u7684\u7528\u6237\uff0c\u5f88\u660e\u663e\uff0c\u540e\u9762\u7684\u4f1a\u6bd4\u524d\u9762\u7684\u66f4\u6709\u6548\u7387\u3002\uff08\u8bf7\u6ce8\u610f\uff0c\u7b2c\u4e00\u6761\u4e2d\u662fSelect *\uff0c\u7b2c\u4e8c\u6761\u662fSelect 1\uff09<\/p>\n
\/\/ \u6ca1\u6709\u6548\u7387\u7684\uff1a\r\n$r = mysql_query(\"SELECT * FROM user WHERE country = 'China'\");\r\nif (mysql_num_rows($r) > 0) {\r\n    \/\/ ...\r\n}\r\n \r\n\/\/ \u6709\u6548\u7387\u7684\uff1a\r\n$r = mysql_query(\"SELECT 1 FROM user WHERE country = 'China' LIMIT 1\");\r\nif (mysql_num_rows($r) > 0) {\r\n    \/\/ ...\r\n}<\/code><\/pre>\n
4. \u4e3a\u641c\u7d22\u5b57\u6bb5\u5efa\u7d22\u5f15<\/h4>\n
\u7d22\u5f15\u5e76\u4e0d\u4e00\u5b9a\u5c31\u662f\u7ed9\u4e3b\u952e\u6216\u662f\u552f\u4e00\u7684\u5b57\u6bb5\u3002\u5982\u679c\u5728\u4f60\u7684\u8868\u4e2d\uff0c\u6709\u67d0\u4e2a\u5b57\u6bb5\u4f60\u603b\u8981\u4f1a\u7ecf\u5e38\u7528\u6765\u505a\u641c\u7d22\uff0c\u90a3\u4e48\uff0c\u8bf7\u4e3a\u5176\u5efa\u7acb\u7d22\u5f15\u5427\u3002<\/p>\n
\"\"<\/div><\/div>\n
\u4ece\u4e0a\u56fe\u4f60\u53ef\u4ee5\u770b\u5230\u90a3\u4e2a\u641c\u7d22\u5b57\u4e32 \u201clast_name LIKE \u2018a%’\u201d\uff0c\u4e00\u4e2a\u662f\u5efa\u4e86\u7d22\u5f15\uff0c\u4e00\u4e2a\u662f\u6ca1\u6709\u7d22\u5f15\uff0c\u6027\u80fd\u5dee\u4e864\u500d\u5de6\u53f3\u3002<\/p>\n
\u53e6\u5916\uff0c\u4f60\u5e94\u8be5\u4e5f\u9700\u8981\u77e5\u9053\u4ec0\u4e48\u6837\u7684\u641c\u7d22\u662f\u4e0d\u80fd\u4f7f\u7528\u6b63\u5e38\u7684\u7d22\u5f15\u7684\u3002\u4f8b\u5982\uff0c\u5f53\u4f60\u9700\u8981\u5728\u4e00\u7bc7\u5927\u7684\u6587\u7ae0\u4e2d\u641c\u7d22\u4e00\u4e2a\u8bcd\u65f6\uff0c\u5982\uff1a \u201cWHERE post_content LIKE \u2018%apple%’\u201d\uff0c\u7d22\u5f15\u53ef\u80fd\u662f\u6ca1\u6709\u610f\u4e49\u7684\u3002\u4f60\u53ef\u80fd\u9700\u8981\u4f7f\u7528MySQL\u5168\u6587\u7d22\u5f15<\/a>\u00a0\u6216\u662f\u81ea\u5df1\u505a\u4e00\u4e2a\u7d22\u5f15\uff08\u6bd4\u5982\u8bf4\uff1a\u641c\u7d22\u5173\u952e\u8bcd\u6216\u662fTag\u4ec0\u4e48\u7684\uff09<\/p>\n
5. \u5728Join\u8868\u7684\u65f6\u5019\u4f7f\u7528\u76f8\u5f53\u7c7b\u578b\u7684\u4f8b\uff0c\u5e76\u5c06\u5176\u7d22\u5f15<\/h4>\n
\u5982\u679c\u4f60\u7684\u5e94\u7528\u7a0b\u5e8f\u6709\u5f88\u591a JOIN \u67e5\u8be2\uff0c\u4f60\u5e94\u8be5\u786e\u8ba4\u4e24\u4e2a\u8868\u4e2dJoin\u7684\u5b57\u6bb5\u662f\u88ab\u5efa\u8fc7\u7d22\u5f15\u7684\u3002\u8fd9\u6837\uff0cMySQL\u5185\u90e8\u4f1a\u542f\u52a8\u4e3a\u4f60\u4f18\u5316Join\u7684SQL\u8bed\u53e5\u7684\u673a\u5236\u3002<\/p>\n
\u800c\u4e14\uff0c\u8fd9\u4e9b\u88ab\u7528\u6765Join\u7684\u5b57\u6bb5\uff0c\u5e94\u8be5\u662f\u76f8\u540c\u7684\u7c7b\u578b\u7684\u3002\u4f8b\u5982\uff1a\u5982\u679c\u4f60\u8981\u628a DECIMAL \u5b57\u6bb5\u548c\u4e00\u4e2a INT \u5b57\u6bb5Join\u5728\u4e00\u8d77\uff0cMySQL\u5c31\u65e0\u6cd5\u4f7f\u7528\u5b83\u4eec\u7684\u7d22\u5f15\u3002\u5bf9\u4e8e\u90a3\u4e9bSTRING\u7c7b\u578b\uff0c\u8fd8\u9700\u8981\u6709\u76f8\u540c\u7684\u5b57\u7b26\u96c6\u624d\u884c\u3002\uff08\u4e24\u4e2a\u8868\u7684\u5b57\u7b26\u96c6\u6709\u53ef\u80fd\u4e0d\u4e00\u6837\uff09<\/p>\n
\/\/ \u5728state\u4e2d\u67e5\u627ecompany\r\n$r = mysql_query(\"SELECT company_name FROM users LEFT JOIN companies ON (users.state = companies.state) WHERE users.id = $user_id\");\r\n \r\n\/\/ \u4e24\u4e2a state \u5b57\u6bb5\u5e94\u8be5\u662f\u88ab\u5efa\u8fc7\u7d22\u5f15\u7684\uff0c\u800c\u4e14\u5e94\u8be5\u662f\u76f8\u5f53\u7684\u7c7b\u578b\uff0c\u76f8\u540c\u7684\u5b57\u7b26\u96c6\u3002<\/code><\/pre>\n
6. \u5343\u4e07\u4e0d\u8981 ORDER BY RAND()<\/h4>\n
\u60f3\u6253\u4e71\u8fd4\u56de\u7684\u6570\u636e\u884c\uff1f\u968f\u673a\u6311\u4e00\u4e2a\u6570\u636e\uff1f\u771f\u4e0d\u77e5\u9053\u8c01\u53d1\u660e\u4e86\u8fd9\u79cd\u7528\u6cd5\uff0c\u4f46\u5f88\u591a\u65b0\u624b\u5f88\u559c\u6b22\u8fd9\u6837\u7528\u3002\u4f46\u4f60\u786e\u4e0d\u4e86\u89e3\u8fd9\u6837\u505a\u6709\u591a\u4e48\u53ef\u6015\u7684\u6027\u80fd\u95ee\u9898\u3002<\/p>\n
\u5982\u679c\u4f60\u771f\u7684\u60f3\u628a\u8fd4\u56de\u7684\u6570\u636e\u884c\u6253\u4e71\u4e86\uff0c\u4f60\u6709N\u79cd\u65b9\u6cd5\u53ef\u4ee5\u8fbe\u5230\u8fd9\u4e2a\u76ee\u7684\u3002\u8fd9\u6837\u4f7f\u7528\u53ea\u8ba9\u4f60\u7684\u6570\u636e\u5e93\u7684\u6027\u80fd\u5448\u6307\u6570\u7ea7\u7684\u4e0b\u964d\u3002\u8fd9\u91cc\u7684\u95ee\u9898\u662f\uff1aMySQL\u4f1a\u4e0d\u5f97\u4e0d\u53bb\u6267\u884cRAND()\u51fd\u6570\uff08\u5f88\u8017CPU\u65f6\u95f4\uff09\uff0c\u800c\u4e14\u8fd9\u662f\u4e3a\u4e86\u6bcf\u4e00\u884c\u8bb0\u5f55\u53bb\u8bb0\u884c\uff0c\u7136\u540e\u518d\u5bf9\u5176\u6392\u5e8f\u3002\u5c31\u7b97\u662f\u4f60\u7528\u4e86Limit 1\u4e5f\u65e0\u6d4e\u4e8e\u4e8b\uff08\u56e0\u4e3a\u8981\u6392\u5e8f\uff09<\/p>\n
\u4e0b\u9762\u7684\u793a\u4f8b\u662f\u968f\u673a\u6311\u4e00\u6761\u8bb0\u5f55<\/p>\n
\/\/ \u5343\u4e07\u4e0d\u8981\u8fd9\u6837\u505a\uff1a\r\n$r = mysql_query(\"SELECT username FROM user ORDER BY RAND() LIMIT 1\");\r\n \r\n\/\/ \u8fd9\u8981\u4f1a\u66f4\u597d\uff1a\r\n$r = mysql_query(\"SELECT count(*) FROM user\");\r\n$d = mysql_fetch_row($r);\r\n$rand = mt_rand(0,$d[0] - 1);\r\n \r\n$r = mysql_query(\"SELECT username FROM user LIMIT $rand, 1\");<\/code><\/pre>\n
7. \u907f\u514d SELECT *<\/h4>\n
\u4ece\u6570\u636e\u5e93\u91cc\u8bfb\u51fa\u8d8a\u591a\u7684\u6570\u636e\uff0c\u90a3\u4e48\u67e5\u8be2\u5c31\u4f1a\u53d8\u5f97\u8d8a\u6162\u3002\u5e76\u4e14\uff0c\u5982\u679c\u4f60\u7684\u6570\u636e\u5e93\u670d\u52a1\u5668\u548cWEB\u670d\u52a1\u5668\u662f\u4e24\u53f0\u72ec\u7acb\u7684\u670d\u52a1\u5668\u7684\u8bdd\uff0c\u8fd9\u8fd8\u4f1a\u589e\u52a0\u7f51\u7edc\u4f20\u8f93\u7684\u8d1f\u8f7d\u3002<\/p>\n
\u6240\u4ee5\uff0c\u4f60\u5e94\u8be5\u517b\u6210\u4e00\u4e2a\u9700\u8981\u4ec0\u4e48\u5c31\u53d6\u4ec0\u4e48\u7684\u597d\u7684\u4e60\u60ef\u3002<\/p>\n
\/\/ \u4e0d\u63a8\u8350\r\n$r = mysql_query(\"SELECT * FROM user WHERE user_id = 1\");\r\n$d = mysql_fetch_assoc($r);\r\necho \"Welcome {$d['username']}\";\r\n \r\n\/\/ \u63a8\u8350\r\n$r = mysql_query(\"SELECT username FROM user WHERE user_id = 1\");\r\n$d = mysql_fetch_assoc($r);\r\necho \"Welcome {$d['username']}\";<\/code><\/pre>\n
8. \u6c38\u8fdc\u4e3a\u6bcf\u5f20\u8868\u8bbe\u7f6e\u4e00\u4e2aID<\/h4>\n
\u6211\u4eec\u5e94\u8be5\u4e3a\u6570\u636e\u5e93\u91cc\u7684\u6bcf\u5f20\u8868\u90fd\u8bbe\u7f6e\u4e00\u4e2aID\u505a\u4e3a\u5176\u4e3b\u952e\uff0c\u800c\u4e14\u6700\u597d\u7684\u662f\u4e00\u4e2aINT\u578b\u7684\uff08\u63a8\u8350\u4f7f\u7528UNSIGNED\uff09\uff0c\u5e76\u8bbe\u7f6e\u4e0a\u81ea\u52a8\u589e\u52a0\u7684AUTO_INCREMENT\u6807\u5fd7\u3002<\/p>\n
\u5c31\u7b97\u662f\u4f60 users \u8868\u6709\u4e00\u4e2a\u4e3b\u952e\u53eb \u201cemail\u201d\u7684\u5b57\u6bb5\uff0c\u4f60\u4e5f\u522b\u8ba9\u5b83\u6210\u4e3a\u4e3b\u952e\u3002\u4f7f\u7528 VARCHAR \u7c7b\u578b\u6765\u5f53\u4e3b\u952e\u4f1a\u4f7f\u7528\u5f97\u6027\u80fd\u4e0b\u964d\u3002\u53e6\u5916\uff0c\u5728\u4f60\u7684\u7a0b\u5e8f\u4e2d\uff0c\u4f60\u5e94\u8be5\u4f7f\u7528\u8868\u7684ID\u6765\u6784\u9020\u4f60\u7684\u6570\u636e\u7ed3\u6784\u3002<\/p>\n
\u800c\u4e14\uff0c\u5728MySQL\u6570\u636e\u5f15\u64ce\u4e0b\uff0c\u8fd8\u6709\u4e00\u4e9b\u64cd\u4f5c\u9700\u8981\u4f7f\u7528\u4e3b\u952e\uff0c\u5728\u8fd9\u4e9b\u60c5\u51b5\u4e0b\uff0c\u4e3b\u952e\u7684\u6027\u80fd\u548c\u8bbe\u7f6e\u53d8\u5f97\u975e\u5e38\u91cd\u8981\uff0c\u6bd4\u5982\uff0c\u96c6\u7fa4\uff0c\u5206\u533a\u2026\u2026<\/p>\n
\u5728\u8fd9\u91cc\uff0c\u53ea\u6709\u4e00\u4e2a\u60c5\u51b5\u662f\u4f8b\u5916\uff0c\u90a3\u5c31\u662f\u201c\u5173\u8054\u8868\u201d\u7684\u201c\u5916\u952e\u201d\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u8fd9\u4e2a\u8868\u7684\u4e3b\u952e\uff0c\u901a\u8fc7\u82e5\u5e72\u4e2a\u522b\u7684\u8868\u7684\u4e3b\u952e\u6784\u6210\u3002\u6211\u4eec\u628a\u8fd9\u4e2a\u60c5\u51b5\u53eb\u505a\u201c\u5916\u952e\u201d\u3002\u6bd4\u5982\uff1a\u6709\u4e00\u4e2a\u201c\u5b66\u751f\u8868\u201d\u6709\u5b66\u751f\u7684ID\uff0c\u6709\u4e00\u4e2a\u201c\u8bfe\u7a0b\u8868\u201d\u6709\u8bfe\u7a0bID\uff0c\u90a3\u4e48\uff0c\u201c\u6210\u7ee9\u8868\u201d\u5c31\u662f\u201c\u5173\u8054\u8868\u201d\u4e86\uff0c\u5176\u5173\u8054\u4e86\u5b66\u751f\u8868\u548c\u8bfe\u7a0b\u8868\uff0c\u5728\u6210\u7ee9\u8868\u4e2d\uff0c\u5b66\u751fID\u548c\u8bfe\u7a0bID\u53eb\u201c\u5916\u952e\u201d\u5176\u5171\u540c\u7ec4\u6210\u4e3b\u952e\u3002<\/p>\n
9. \u4f7f\u7528 ENUM \u800c\u4e0d\u662f VARCHAR<\/h4>\n
ENUM<\/a>\u00a0\u7c7b\u578b\u662f\u975e\u5e38\u5feb\u548c\u7d27\u51d1\u7684\u3002\u5728\u5b9e\u9645\u4e0a\uff0c\u5176\u4fdd\u5b58\u7684\u662f TINYINT\uff0c\u4f46\u5176\u5916\u8868\u4e0a\u663e\u793a\u4e3a\u5b57\u7b26\u4e32\u3002\u8fd9\u6837\u4e00\u6765\uff0c\u7528\u8fd9\u4e2a\u5b57\u6bb5\u6765\u505a\u4e00\u4e9b\u9009\u9879\u5217\u8868\u53d8\u5f97\u76f8\u5f53\u7684\u5b8c\u7f8e\u3002<\/p>\n
\u5982\u679c\u4f60\u6709\u4e00\u4e2a\u5b57\u6bb5\uff0c\u6bd4\u5982\u201c\u6027\u522b\u201d\uff0c\u201c\u56fd\u5bb6\u201d\uff0c\u201c\u6c11\u65cf\u201d\uff0c\u201c\u72b6\u6001\u201d\u6216\u201c\u90e8\u95e8\u201d\uff0c\u4f60\u77e5\u9053\u8fd9\u4e9b\u5b57\u6bb5\u7684\u53d6\u503c\u662f\u6709\u9650\u800c\u4e14\u56fa\u5b9a\u7684\uff0c\u90a3\u4e48\uff0c\u4f60\u5e94\u8be5\u4f7f\u7528 ENUM \u800c\u4e0d\u662f VARCHAR\u3002<\/p>\n
MySQL\u4e5f\u6709\u4e00\u4e2a\u201c\u5efa\u8bae\u201d\uff08\u89c1\u7b2c\u5341\u6761\uff09\u544a\u8bc9\u4f60\u600e\u4e48\u53bb\u91cd\u65b0\u7ec4\u7ec7\u4f60\u7684\u8868\u7ed3\u6784\u3002\u5f53\u4f60\u6709\u4e00\u4e2a VARCHAR \u5b57\u6bb5\u65f6\uff0c\u8fd9\u4e2a\u5efa\u8bae\u4f1a\u544a\u8bc9\u4f60\u628a\u5176\u6539\u6210 ENUM \u7c7b\u578b\u3002\u4f7f\u7528 PROCEDURE ANALYSE() \u4f60\u53ef\u4ee5\u5f97\u5230\u76f8\u5173\u7684\u5efa\u8bae\u3002<\/p>\n
10. \u4ece PROCEDURE ANALYSE() \u53d6\u5f97\u5efa\u8bae<\/h4>\n
PROCEDURE ANALYSE()<\/a>\u00a0\u4f1a\u8ba9 MySQL \u5e2e\u4f60\u53bb\u5206\u6790\u4f60\u7684\u5b57\u6bb5\u548c\u5176\u5b9e\u9645\u7684\u6570\u636e\uff0c\u5e76\u4f1a\u7ed9\u4f60\u4e00\u4e9b\u6709\u7528\u7684\u5efa\u8bae\u3002\u53ea\u6709\u8868\u4e2d\u6709\u5b9e\u9645\u7684\u6570\u636e\uff0c\u8fd9\u4e9b\u5efa\u8bae\u624d\u4f1a\u53d8\u5f97\u6709\u7528\uff0c\u56e0\u4e3a\u8981\u505a\u4e00\u4e9b\u5927\u7684\u51b3\u5b9a\u662f\u9700\u8981\u6709\u6570\u636e\u4f5c\u4e3a\u57fa\u7840\u7684\u3002<\/p>\n
\u4f8b\u5982\uff0c\u5982\u679c\u4f60\u521b\u5efa\u4e86\u4e00\u4e2a INT \u5b57\u6bb5\u4f5c\u4e3a\u4f60\u7684\u4e3b\u952e\uff0c\u7136\u800c\u5e76\u6ca1\u6709\u592a\u591a\u7684\u6570\u636e\uff0c\u90a3\u4e48\uff0cPROCEDURE ANALYSE()\u4f1a\u5efa\u8bae\u4f60\u628a\u8fd9\u4e2a\u5b57\u6bb5\u7684\u7c7b\u578b\u6539\u6210 MEDIUMINT \u3002\u6216\u662f\u4f60\u4f7f\u7528\u4e86\u4e00\u4e2a VARCHAR \u5b57\u6bb5\uff0c\u56e0\u4e3a\u6570\u636e\u4e0d\u591a\uff0c\u4f60\u53ef\u80fd\u4f1a\u5f97\u5230\u4e00\u4e2a\u8ba9\u4f60\u628a\u5b83\u6539\u6210 ENUM \u7684\u5efa\u8bae\u3002\u8fd9\u4e9b\u5efa\u8bae\uff0c\u90fd\u662f\u53ef\u80fd\u56e0\u4e3a\u6570\u636e\u4e0d\u591f\u591a\uff0c\u6240\u4ee5\u51b3\u7b56\u505a\u5f97\u5c31\u4e0d\u591f\u51c6\u3002<\/p>\n
\u5728phpmyadmin\u91cc\uff0c\u4f60\u53ef\u4ee5\u5728\u67e5\u770b\u8868\u65f6\uff0c\u70b9\u51fb \u201cPropose table structure\u201d \u6765\u67e5\u770b\u8fd9\u4e9b\u5efa\u8bae<\/p>\n
\"\"<\/div><\/div>\n
\u4e00\u5b9a\u8981\u6ce8\u610f\uff0c\u8fd9\u4e9b\u53ea\u662f\u5efa\u8bae\uff0c\u53ea\u6709\u5f53\u4f60\u7684\u8868\u91cc\u7684\u6570\u636e\u8d8a\u6765\u8d8a\u591a\u65f6\uff0c\u8fd9\u4e9b\u5efa\u8bae\u624d\u4f1a\u53d8\u5f97\u51c6\u786e\u3002\u4e00\u5b9a\u8981\u8bb0\u4f4f\uff0c\u4f60\u624d\u662f\u6700\u7ec8\u505a\u51b3\u5b9a\u7684\u4eba\u3002<\/p>\n
11. \u5c3d\u53ef\u80fd\u7684\u4f7f\u7528 NOT NULL<\/h4>\n
\u9664\u975e\u4f60\u6709\u4e00\u4e2a\u5f88\u7279\u522b\u7684\u539f\u56e0\u53bb\u4f7f\u7528 NULL \u503c\uff0c\u4f60\u5e94\u8be5\u603b\u662f\u8ba9\u4f60\u7684\u5b57\u6bb5\u4fdd\u6301 NOT NULL\u3002\u8fd9\u770b\u8d77\u6765\u597d\u50cf\u6709\u70b9\u4e89\u8bae\uff0c\u8bf7\u5f80\u4e0b\u770b\u3002<\/p>\n
\u9996\u5148\uff0c\u95ee\u95ee\u4f60\u81ea\u5df1\u201cEmpty\u201d\u548c\u201cNULL\u201d\u6709\u591a\u5927\u7684\u533a\u522b\uff08\u5982\u679c\u662fINT\uff0c\u90a3\u5c31\u662f0\u548cNULL\uff09\uff1f\u5982\u679c\u4f60\u89c9\u5f97\u5b83\u4eec\u4e4b\u95f4\u6ca1\u6709\u4ec0\u4e48\u533a\u522b\uff0c\u90a3\u4e48\u4f60\u5c31\u4e0d\u8981\u4f7f\u7528NULL\u3002\uff08\u4f60\u77e5\u9053\u5417\uff1f\u5728 Oracle \u91cc\uff0cNULL \u548c Empty \u7684\u5b57\u7b26\u4e32\u662f\u4e00\u6837\u7684\uff01)<\/p>\n
\u4e0d\u8981\u4ee5\u4e3a NULL \u4e0d\u9700\u8981\u7a7a\u95f4\uff0c\u5176\u9700\u8981\u989d\u5916\u7684\u7a7a\u95f4\uff0c\u5e76\u4e14\uff0c\u5728\u4f60\u8fdb\u884c\u6bd4\u8f83\u7684\u65f6\u5019\uff0c\u4f60\u7684\u7a0b\u5e8f\u4f1a\u66f4\u590d\u6742\u3002 \u5f53\u7136\uff0c\u8fd9\u91cc\u5e76\u4e0d\u662f\u8bf4\u4f60\u5c31\u4e0d\u80fd\u4f7f\u7528NULL\u4e86\uff0c\u73b0\u5b9e\u60c5\u51b5\u662f\u5f88\u590d\u6742\u7684\uff0c\u4f9d\u7136\u4f1a\u6709\u4e9b\u60c5\u51b5\u4e0b\uff0c\u4f60\u9700\u8981\u4f7f\u7528NULL\u503c\u3002<\/p>\n
\u4e0b\u9762\u6458\u81eaMySQL\u81ea\u5df1\u7684\u6587\u6863\uff1a<\/p>\n
\n
\u201cNULL columns require additional space in the row to record whether their values are NULL. For MyISAM tables, each NULL column takes one bit extra, rounded up to the nearest byte.\u201d<\/p>\n<\/blockquote>\n
12. Prepared Statements<\/h4>\n
Prepared Statements\u5f88\u50cf\u5b58\u50a8\u8fc7\u7a0b\uff0c\u662f\u4e00\u79cd\u8fd0\u884c\u5728\u540e\u53f0\u7684SQL\u8bed\u53e5\u96c6\u5408\uff0c\u6211\u4eec\u53ef\u4ee5\u4ece\u4f7f\u7528 prepared statements \u83b7\u5f97\u5f88\u591a\u597d\u5904\uff0c\u65e0\u8bba\u662f\u6027\u80fd\u95ee\u9898\u8fd8\u662f\u5b89\u5168\u95ee\u9898\u3002<\/p>\n
Prepared Statements \u53ef\u4ee5\u68c0\u67e5\u4e00\u4e9b\u4f60\u7ed1\u5b9a\u597d\u7684\u53d8\u91cf\uff0c\u8fd9\u6837\u53ef\u4ee5\u4fdd\u62a4\u4f60\u7684\u7a0b\u5e8f\u4e0d\u4f1a\u53d7\u5230\u201cSQL\u6ce8\u5165\u5f0f\u201d\u653b\u51fb\u3002\u5f53\u7136\uff0c\u4f60\u4e5f\u53ef\u4ee5\u624b\u52a8\u5730\u68c0\u67e5\u4f60\u7684\u8fd9\u4e9b\u53d8\u91cf\uff0c\u7136\u800c\uff0c\u624b\u52a8\u7684\u68c0\u67e5\u5bb9\u6613\u51fa\u95ee\u9898\uff0c\u800c\u4e14\u5f88\u7ecf\u5e38\u4f1a\u88ab\u7a0b\u5e8f\u5458\u5fd8\u4e86\u3002\u5f53\u6211\u4eec\u4f7f\u7528\u4e00\u4e9bframework\u6216\u662fORM\u7684\u65f6\u5019\uff0c\u8fd9\u6837\u7684\u95ee\u9898\u4f1a\u597d\u4e00\u4e9b\u3002<\/p>\n
\u5728\u6027\u80fd\u65b9\u9762\uff0c\u5f53\u4e00\u4e2a\u76f8\u540c\u7684\u67e5\u8be2\u88ab\u4f7f\u7528\u591a\u6b21\u7684\u65f6\u5019\uff0c\u8fd9\u4f1a\u4e3a\u4f60\u5e26\u6765\u53ef\u89c2\u7684\u6027\u80fd\u4f18\u52bf\u3002\u4f60\u53ef\u4ee5\u7ed9\u8fd9\u4e9bPrepared Statements\u5b9a\u4e49\u4e00\u4e9b\u53c2\u6570\uff0c\u800cMySQL\u53ea\u4f1a\u89e3\u6790\u4e00\u6b21\u3002<\/p>\n
\u867d\u7136\u6700\u65b0\u7248\u672c\u7684MySQL\u5728\u4f20\u8f93Prepared Statements\u662f\u4f7f\u7528\u4e8c\u8fdb\u5236\u5f62\u52bf\uff0c\u6240\u4ee5\u8fd9\u4f1a\u4f7f\u5f97\u7f51\u7edc\u4f20\u8f93\u975e\u5e38\u6709\u6548\u7387\u3002<\/p>\n
\u5f53\u7136\uff0c\u4e5f\u6709\u4e00\u4e9b\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u9700\u8981\u907f\u514d\u4f7f\u7528Prepared Statements\uff0c\u56e0\u4e3a\u5176\u4e0d\u652f\u6301\u67e5\u8be2\u7f13\u5b58\u3002\u4f46\u636e\u8bf4\u7248\u672c5.1\u540e\u652f\u6301\u4e86\u3002<\/p>\n
\u5728PHP\u4e2d\u8981\u4f7f\u7528prepared statements\uff0c\u4f60\u53ef\u4ee5\u67e5\u770b\u5176\u4f7f\u7528\u624b\u518c\uff1amysqli \u6269\u5c55<\/a>\u00a0\u6216\u662f\u4f7f\u7528\u6570\u636e\u5e93\u62bd\u8c61\u5c42\uff0c\u5982\uff1a\u00a0PDO<\/a>.<\/p>\n
\/\/ \u521b\u5efa prepared statement\r\nif ($stmt = $mysqli->prepare(\"SELECT username FROM user WHERE state=?\")) {\r\n \r\n    \/\/ \u7ed1\u5b9a\u53c2\u6570\r\n    $stmt->bind_param(\"s\", $state);\r\n \r\n    \/\/ \u6267\u884c\r\n    $stmt->execute();\r\n \r\n    \/\/ \u7ed1\u5b9a\u7ed3\u679c\r\n    $stmt->bind_result($username);\r\n \r\n    \/\/ \u79fb\u52a8\u6e38\u6807\r\n    $stmt->fetch();\r\n \r\n    printf(\"%s is from %s\\n\", $username, $state);\r\n \r\n    $stmt->close();\r\n}<\/code><\/pre>\n
13. \u65e0\u7f13\u51b2\u7684\u67e5\u8be2<\/h4>\n
\u6b63\u5e38\u7684\u60c5\u51b5\u4e0b\uff0c\u5f53\u4f60\u5728\u5f53\u4f60\u5728\u4f60\u7684\u811a\u672c\u4e2d\u6267\u884c\u4e00\u4e2aSQL\u8bed\u53e5\u7684\u65f6\u5019\uff0c\u4f60\u7684\u7a0b\u5e8f\u4f1a\u505c\u5728\u90a3\u91cc\u76f4\u5230\u6ca1\u8fd9\u4e2aSQL\u8bed\u53e5\u8fd4\u56de\uff0c\u7136\u540e\u4f60\u7684\u7a0b\u5e8f\u518d\u5f80\u4e0b\u7ee7\u7eed\u6267\u884c\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u65e0\u7f13\u51b2\u67e5\u8be2\u6765\u6539\u53d8\u8fd9\u4e2a\u884c\u4e3a\u3002<\/p>\n
\u5173\u4e8e\u8fd9\u4e2a\u4e8b\u60c5\uff0c\u5728PHP\u7684\u6587\u6863\u4e2d\u6709\u4e00\u4e2a\u975e\u5e38\u4e0d\u9519\u7684\u8bf4\u660e\uff1amysql_unbuffered_query()<\/a>\u00a0\u51fd\u6570\uff1a<\/p>\n
\n
\u201cmysql_unbuffered_query() sends the SQL query query to MySQL without automatically fetching and buffering the result rows as mysql_query() does. This saves a considerable amount of memory with SQL queries that produce large result sets, and you can start working on the result set immediately after the first row has been retrieved as you don\u2019t have to wait until the complete SQL query has been performed.\u201d<\/p>\n<\/blockquote>\n
\u4e0a\u9762\u90a3\u53e5\u8bdd\u7ffb\u8bd1\u8fc7\u6765\u662f\u8bf4\uff0cmysql_unbuffered_query() \u53d1\u9001\u4e00\u4e2aSQL\u8bed\u53e5\u5230MySQL\u800c\u5e76\u4e0d\u50cfmysql_query()\u4e00\u6837\u53bb\u81ea\u52a8fethch\u548c\u7f13\u5b58\u7ed3\u679c\u3002\u8fd9\u4f1a\u76f8\u5f53\u8282\u7ea6\u5f88\u591a\u53ef\u89c2\u7684\u5185\u5b58\uff0c\u5c24\u5176\u662f\u90a3\u4e9b\u4f1a\u4ea7\u751f\u5927\u91cf\u7ed3\u679c\u7684\u67e5\u8be2\u8bed\u53e5\uff0c\u5e76\u4e14\uff0c\u4f60\u4e0d\u9700\u8981\u7b49\u5230\u6240\u6709\u7684\u7ed3\u679c\u90fd\u8fd4\u56de\uff0c\u53ea\u9700\u8981\u7b2c\u4e00\u884c\u6570\u636e\u8fd4\u56de\u7684\u65f6\u5019\uff0c\u4f60\u5c31\u53ef\u4ee5\u5f00\u59cb\u9a6c\u4e0a\u5f00\u59cb\u5de5\u4f5c\u4e8e\u67e5\u8be2\u7ed3\u679c\u4e86\u3002<\/p>\n
\u7136\u800c\uff0c\u8fd9\u4f1a\u6709\u4e00\u4e9b\u9650\u5236\u3002\u56e0\u4e3a\u4f60\u8981\u4e48\u628a\u6240\u6709\u884c\u90fd\u8bfb\u8d70\uff0c\u6216\u662f\u4f60\u8981\u5728\u8fdb\u884c\u4e0b\u4e00\u6b21\u7684\u67e5\u8be2\u524d\u8c03\u7528\u00a0mysql_free_result()<\/a>\u00a0\u6e05\u9664\u7ed3\u679c\u3002\u800c\u4e14\uff0cmysql_num_rows()<\/a>\u00a0\u6216\u00a0mysql_data_seek()<\/a>\u00a0\u5c06\u65e0\u6cd5\u4f7f\u7528\u3002\u6240\u4ee5\uff0c\u662f\u5426\u4f7f\u7528\u65e0\u7f13\u51b2\u7684\u67e5\u8be2\u4f60\u9700\u8981\u4ed4\u7ec6\u8003\u8651\u3002<\/p>\n
14. \u628aIP\u5730\u5740\u5b58\u6210 UNSIGNED INT<\/h4>\n
\u5f88\u591a\u7a0b\u5e8f\u5458\u90fd\u4f1a\u521b\u5efa\u4e00\u4e2a VARCHAR(15) \u5b57\u6bb5\u6765\u5b58\u653e\u5b57\u7b26\u4e32\u5f62\u5f0f\u7684IP\u800c\u4e0d\u662f\u6574\u5f62\u7684IP\u3002\u5982\u679c\u4f60\u7528\u6574\u5f62\u6765\u5b58\u653e\uff0c\u53ea\u9700\u89814\u4e2a\u5b57\u8282\uff0c\u5e76\u4e14\u4f60\u53ef\u4ee5\u6709\u5b9a\u957f\u7684\u5b57\u6bb5\u3002\u800c\u4e14\uff0c\u8fd9\u4f1a\u4e3a\u4f60\u5e26\u6765\u67e5\u8be2\u4e0a\u7684\u4f18\u52bf\uff0c\u5c24\u5176\u662f\u5f53\u4f60\u9700\u8981\u4f7f\u7528\u8fd9\u6837\u7684WHERE\u6761\u4ef6\uff1aIP between ip1 and ip2\u3002<\/p>\n
\u6211\u4eec\u5fc5\u9700\u8981\u4f7f\u7528UNSIGNED INT\uff0c\u56e0\u4e3a IP\u5730\u5740\u4f1a\u4f7f\u7528\u6574\u4e2a32\u4f4d\u7684\u65e0\u7b26\u53f7\u6574\u5f62\u3002<\/p>\n
\u800c\u4f60\u7684\u67e5\u8be2\uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528\u00a0INET_ATON()<\/a>\u00a0\u6765\u628a\u4e00\u4e2a\u5b57\u7b26\u4e32IP\u8f6c\u6210\u4e00\u4e2a\u6574\u5f62\uff0c\u5e76\u4f7f\u7528\u00a0INET_NTOA()<\/a>\u00a0\u628a\u4e00\u4e2a\u6574\u5f62\u8f6c\u6210\u4e00\u4e2a\u5b57\u7b26\u4e32IP\u3002\u5728PHP\u4e2d\uff0c\u4e5f\u6709\u8fd9\u6837\u7684\u51fd\u6570\u00a0ip2long()<\/a>\u00a0\u548c\u00a0long2ip()<\/a>\u3002<\/p>\n
$r = \"UPDATE users SET ip = INET_ATON('{$_SERVER['REMOTE_ADDR']}') WHERE user_id = $user_id\";<\/code><\/pre>\n
15. \u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4f1a\u66f4\u5feb<\/h4>\n
\u5982\u679c\u8868\u4e2d\u7684\u6240\u6709\u5b57\u6bb5\u90fd\u662f\u201c\u56fa\u5b9a\u957f\u5ea6\u201d\u7684\uff0c\u6574\u4e2a\u8868\u4f1a\u88ab\u8ba4\u4e3a\u662f\u00a0\u201cstatic\u201d \u6216 \u201cfixed-length\u201d<\/a>\u3002 \u4f8b\u5982\uff0c\u8868\u4e2d\u6ca1\u6709\u5982\u4e0b\u7c7b\u578b\u7684\u5b57\u6bb5\uff1a VARCHAR\uff0cTEXT\uff0cBLOB\u3002\u53ea\u8981\u4f60\u5305\u62ec\u4e86\u5176\u4e2d\u4e00\u4e2a\u8fd9\u4e9b\u5b57\u6bb5\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8868\u5c31\u4e0d\u662f\u201c\u56fa\u5b9a\u957f\u5ea6\u9759\u6001\u8868\u201d\u4e86\uff0c\u8fd9\u6837\uff0cMySQL \u5f15\u64ce\u4f1a\u7528\u53e6\u4e00\u79cd\u65b9\u6cd5\u6765\u5904\u7406\u3002<\/p>\n
\u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4f1a\u63d0\u9ad8\u6027\u80fd\uff0c\u56e0\u4e3aMySQL\u641c\u5bfb\u5f97\u4f1a\u66f4\u5feb\u4e00\u4e9b\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u56fa\u5b9a\u7684\u957f\u5ea6\u662f\u5f88\u5bb9\u6613\u8ba1\u7b97\u4e0b\u4e00\u4e2a\u6570\u636e\u7684\u504f\u79fb\u91cf\u7684\uff0c\u6240\u4ee5\u8bfb\u53d6\u7684\u81ea\u7136\u4e5f\u4f1a\u5f88\u5feb\u3002\u800c\u5982\u679c\u5b57\u6bb5\u4e0d\u662f\u5b9a\u957f\u7684\uff0c\u90a3\u4e48\uff0c\u6bcf\u4e00\u6b21\u8981\u627e\u4e0b\u4e00\u6761\u7684\u8bdd\uff0c\u9700\u8981\u7a0b\u5e8f\u627e\u5230\u4e3b\u952e\u3002<\/p>\n
\u5e76\u4e14\uff0c\u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4e5f\u66f4\u5bb9\u6613\u88ab\u7f13\u5b58\u548c\u91cd\u5efa\u3002\u4e0d\u8fc7\uff0c\u552f\u4e00\u7684\u526f\u4f5c\u7528\u662f\uff0c\u56fa\u5b9a\u957f\u5ea6\u7684\u5b57\u6bb5\u4f1a\u6d6a\u8d39\u4e00\u4e9b\u7a7a\u95f4\uff0c\u56e0\u4e3a\u5b9a\u957f\u7684\u5b57\u6bb5\u65e0\u8bba\u4f60\u7528\u4e0d\u7528\uff0c\u4ed6\u90fd\u662f\u8981\u5206\u914d\u90a3\u4e48\u591a\u7684\u7a7a\u95f4\u3002<\/p>\n
\u4f7f\u7528\u201c\u5782\u76f4\u5206\u5272\u201d\u6280\u672f\uff08\u89c1\u4e0b\u4e00\u6761\uff09\uff0c\u4f60\u53ef\u4ee5\u5206\u5272\u4f60\u7684\u8868\u6210\u4e3a\u4e24\u4e2a\u4e00\u4e2a\u662f\u5b9a\u957f\u7684\uff0c\u4e00\u4e2a\u5219\u662f\u4e0d\u5b9a\u957f\u7684\u3002<\/p>\n
16. \u5782\u76f4\u5206\u5272<\/h4>\n
\u201c\u5782\u76f4\u5206\u5272\u201d\u662f\u4e00\u79cd\u628a\u6570\u636e\u5e93\u4e2d\u7684\u8868\u6309\u5217\u53d8\u6210\u51e0\u5f20\u8868\u7684\u65b9\u6cd5\uff0c\u8fd9\u6837\u53ef\u4ee5\u964d\u4f4e\u8868\u7684\u590d\u6742\u5ea6\u548c\u5b57\u6bb5\u7684\u6570\u76ee\uff0c\u4ece\u800c\u8fbe\u5230\u4f18\u5316\u7684\u76ee\u7684\u3002\uff08\u4ee5\u524d\uff0c\u5728\u94f6\u884c\u505a\u8fc7\u9879\u76ee\uff0c\u89c1\u8fc7\u4e00\u5f20\u8868\u6709100\u591a\u4e2a\u5b57\u6bb5\uff0c\u5f88\u6050\u6016\uff09<\/p>\n
\u793a\u4f8b\u4e00<\/strong>\uff1a\u5728Users\u8868\u4e2d\u6709\u4e00\u4e2a\u5b57\u6bb5\u662f\u5bb6\u5ead\u5730\u5740\uff0c\u8fd9\u4e2a\u5b57\u6bb5\u662f\u53ef\u9009\u5b57\u6bb5\uff0c\u76f8\u6bd4\u8d77\uff0c\u800c\u4e14\u4f60\u5728\u6570\u636e\u5e93\u64cd\u4f5c\u7684\u65f6\u5019\u9664\u4e86\u4e2a\u4eba\u4fe1\u606f\u5916\uff0c\u4f60\u5e76\u4e0d\u9700\u8981\u7ecf\u5e38\u8bfb\u53d6\u6216\u662f\u6539\u5199\u8fd9\u4e2a\u5b57\u6bb5\u3002\u90a3\u4e48\uff0c\u4e3a\u4ec0\u4e48\u4e0d\u628a\u4ed6\u653e\u5230\u53e6\u5916\u4e00\u5f20\u8868\u4e2d\u5462\uff1f \u8fd9\u6837\u4f1a\u8ba9\u4f60\u7684\u8868\u6709\u66f4\u597d\u7684\u6027\u80fd\uff0c\u5927\u5bb6\u60f3\u60f3\u662f\u4e0d\u662f\uff0c\u5927\u91cf\u7684\u65f6\u5019\uff0c\u6211\u5bf9\u4e8e\u7528\u6237\u8868\u6765\u8bf4\uff0c\u53ea\u6709\u7528\u6237ID\uff0c\u7528\u6237\u540d\uff0c\u53e3\u4ee4\uff0c\u7528\u6237\u89d2\u8272\u7b49\u4f1a\u88ab\u7ecf\u5e38\u4f7f\u7528\u3002\u5c0f\u4e00\u70b9\u7684\u8868\u603b\u662f\u4f1a\u6709\u597d\u7684\u6027\u80fd\u3002<\/p>\n
\u793a\u4f8b\u4e8c<\/strong>\uff1a \u4f60\u6709\u4e00\u4e2a\u53eb \u201clast_login\u201d \u7684\u5b57\u6bb5\uff0c\u5b83\u4f1a\u5728\u6bcf\u6b21\u7528\u6237\u767b\u5f55\u65f6\u88ab\u66f4\u65b0\u3002\u4f46\u662f\uff0c\u6bcf\u6b21\u66f4\u65b0\u65f6\u4f1a\u5bfc\u81f4\u8be5\u8868\u7684\u67e5\u8be2\u7f13\u5b58\u88ab\u6e05\u7a7a\u3002\u6240\u4ee5\uff0c\u4f60\u53ef\u4ee5\u628a\u8fd9\u4e2a\u5b57\u6bb5\u653e\u5230\u53e6\u4e00\u4e2a\u8868\u4e2d\uff0c\u8fd9\u6837\u5c31\u4e0d\u4f1a\u5f71\u54cd\u4f60\u5bf9\u7528\u6237ID\uff0c\u7528\u6237\u540d\uff0c\u7528\u6237\u89d2\u8272\u7684\u4e0d\u505c\u5730\u8bfb\u53d6\u4e86\uff0c\u56e0\u4e3a\u67e5\u8be2\u7f13\u5b58\u4f1a\u5e2e\u4f60\u589e\u52a0\u5f88\u591a\u6027\u80fd\u3002<\/p>\n
\u53e6\u5916\uff0c\u4f60\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u8fd9\u4e9b\u88ab\u5206\u51fa\u53bb\u7684\u5b57\u6bb5\u6240\u5f62\u6210\u7684\u8868\uff0c\u4f60\u4e0d\u4f1a\u7ecf\u5e38\u6027\u5730\u53bbJoin\u4ed6\u4eec\uff0c\u4e0d\u7136\u7684\u8bdd\uff0c\u8fd9\u6837\u7684\u6027\u80fd\u4f1a\u6bd4\u4e0d\u5206\u5272\u65f6\u8fd8\u8981\u5dee\uff0c\u800c\u4e14\uff0c\u4f1a\u662f\u6781\u6570\u7ea7\u7684\u4e0b\u964d\u3002<\/p>\n
17. \u62c6\u5206\u5927\u7684 DELETE \u6216 INSERT \u8bed\u53e5<\/h4>\n
\u5982\u679c\u4f60\u9700\u8981\u5728\u4e00\u4e2a\u5728\u7ebf\u7684\u7f51\u7ad9\u4e0a\u53bb\u6267\u884c\u4e00\u4e2a\u5927\u7684 DELETE \u6216 INSERT \u67e5\u8be2\uff0c\u4f60\u9700\u8981\u975e\u5e38\u5c0f\u5fc3\uff0c\u8981\u907f\u514d\u4f60\u7684\u64cd\u4f5c\u8ba9\u4f60\u7684\u6574\u4e2a\u7f51\u7ad9\u505c\u6b62\u76f8\u5e94\u3002\u56e0\u4e3a\u8fd9\u4e24\u4e2a\u64cd\u4f5c\u662f\u4f1a\u9501\u8868\u7684\uff0c\u8868\u4e00\u9501\u4f4f\u4e86\uff0c\u522b\u7684\u64cd\u4f5c\u90fd\u8fdb\u4e0d\u6765\u4e86\u3002<\/p>\n
Apache \u4f1a\u6709\u5f88\u591a\u7684\u5b50\u8fdb\u7a0b\u6216\u7ebf\u7a0b\u3002\u6240\u4ee5\uff0c\u5176\u5de5\u4f5c\u8d77\u6765\u76f8\u5f53\u6709\u6548\u7387\uff0c\u800c\u6211\u4eec\u7684\u670d\u52a1\u5668\u4e5f\u4e0d\u5e0c\u671b\u6709\u592a\u591a\u7684\u5b50\u8fdb\u7a0b\uff0c\u7ebf\u7a0b\u548c\u6570\u636e\u5e93\u94fe\u63a5\uff0c\u8fd9\u662f\u6781\u5927\u7684\u5360\u670d\u52a1\u5668\u8d44\u6e90\u7684\u4e8b\u60c5\uff0c\u5c24\u5176\u662f\u5185\u5b58\u3002<\/p>\n
\u5982\u679c\u4f60\u628a\u4f60\u7684\u8868\u9501\u4e0a\u4e00\u6bb5\u65f6\u95f4\uff0c\u6bd4\u598230\u79d2\u949f\uff0c\u90a3\u4e48\u5bf9\u4e8e\u4e00\u4e2a\u6709\u5f88\u9ad8\u8bbf\u95ee\u91cf\u7684\u7ad9\u70b9\u6765\u8bf4\uff0c\u8fd930\u79d2\u6240\u79ef\u7d2f\u7684\u8bbf\u95ee\u8fdb\u7a0b\/\u7ebf\u7a0b\uff0c\u6570\u636e\u5e93\u94fe\u63a5\uff0c\u6253\u5f00\u7684\u6587\u4ef6\u6570\uff0c\u53ef\u80fd\u4e0d\u4ec5\u4ec5\u4f1a\u8ba9\u4f60\u6ccaWEB\u670d\u52a1Crash\uff0c\u8fd8\u53ef\u80fd\u4f1a\u8ba9\u4f60\u7684\u6574\u53f0\u670d\u52a1\u5668\u9a6c\u4e0a\u639b\u4e86\u3002<\/p>\n
\u6240\u4ee5\uff0c\u5982\u679c\u4f60\u6709\u4e00\u4e2a\u5927\u7684\u5904\u7406\uff0c\u4f60\u5b9a\u4f60\u4e00\u5b9a\u628a\u5176\u62c6\u5206\uff0c\u4f7f\u7528 LIMIT \u6761\u4ef6\u662f\u4e00\u4e2a\u597d\u7684\u65b9\u6cd5\u3002\u4e0b\u9762\u662f\u4e00\u4e2a\u793a\u4f8b\uff1a<\/p>\n
while (1) {\r\n    \/\/\u6bcf\u6b21\u53ea\u505a1000\u6761\r\n    mysql_query(\"DELETE FROM logs WHERE log_date <= '2009-11-01' LIMIT 1000\");\r\n    if (mysql_affected_rows() == 0) {\r\n        \/\/ \u6ca1\u5f97\u53ef\u5220\u4e86\uff0c\u9000\u51fa\uff01\r\n        break;\r\n    }\r\n    \/\/ \u6bcf\u6b21\u90fd\u8981\u4f11\u606f\u4e00\u4f1a\u513f\r\n    usleep(50000);\r\n}<\/code><\/pre>\n
18. \u8d8a\u5c0f\u7684\u5217\u4f1a\u8d8a\u5feb<\/h4>\n
\u5bf9\u4e8e\u5927\u591a\u6570\u7684\u6570\u636e\u5e93\u5f15\u64ce\u6765\u8bf4\uff0c\u786c\u76d8\u64cd\u4f5c\u53ef\u80fd\u662f\u6700\u91cd\u5927\u7684\u74f6\u9888\u3002\u6240\u4ee5\uff0c\u628a\u4f60\u7684\u6570\u636e\u53d8\u5f97\u7d27\u51d1\u4f1a\u5bf9\u8fd9\u79cd\u60c5\u51b5\u975e\u5e38\u6709\u5e2e\u52a9\uff0c\u56e0\u4e3a\u8fd9\u51cf\u5c11\u4e86\u5bf9\u786c\u76d8\u7684\u8bbf\u95ee\u3002<\/p>\n
\u53c2\u770b MySQL \u7684\u6587\u6863\u00a0Storage Requirements<\/a>\u00a0\u67e5\u770b\u6240\u6709\u7684\u6570\u636e\u7c7b\u578b\u3002<\/p>\n
\u5982\u679c\u4e00\u4e2a\u8868\u53ea\u4f1a\u6709\u51e0\u5217\u7f62\u4e86\uff08\u6bd4\u5982\u8bf4\u5b57\u5178\u8868\uff0c\u914d\u7f6e\u8868\uff09\uff0c\u90a3\u4e48\uff0c\u6211\u4eec\u5c31\u6ca1\u6709\u7406\u7531\u4f7f\u7528 INT \u6765\u505a\u4e3b\u952e\uff0c\u4f7f\u7528 MEDIUMINT, SMALLINT \u6216\u662f\u66f4\u5c0f\u7684 TINYINT \u4f1a\u66f4\u7ecf\u6d4e\u4e00\u4e9b\u3002\u5982\u679c\u4f60\u4e0d\u9700\u8981\u8bb0\u5f55\u65f6\u95f4\uff0c\u4f7f\u7528 DATE \u8981\u6bd4 DATETIME \u597d\u5f97\u591a\u3002<\/p>\n
\u5f53\u7136\uff0c\u4f60\u4e5f\u9700\u8981\u7559\u591f\u8db3\u591f\u7684\u6269\u5c55\u7a7a\u95f4\uff0c\u4e0d\u7136\uff0c\u4f60\u65e5\u540e\u6765\u5e72\u8fd9\u4e2a\u4e8b\uff0c\u4f60\u4f1a\u6b7b\u7684\u5f88\u96be\u770b\uff0c\u53c2\u770bSlashdot\u7684\u4f8b\u5b50<\/a>\uff082009\u5e7411\u670806\u65e5\uff09\uff0c\u4e00\u4e2a\u7b80\u5355\u7684ALTER TABLE\u8bed\u53e5\u82b1\u4e863\u4e2a\u591a\u5c0f\u65f6\uff0c\u56e0\u4e3a\u91cc\u9762\u6709\u4e00\u5343\u516d\u767e\u4e07\u6761\u6570\u636e\u3002<\/p>\n
19. \u9009\u62e9\u6b63\u786e\u7684\u5b58\u50a8\u5f15\u64ce<\/h4>\n
\u5728 MySQL \u4e2d\u6709\u4e24\u4e2a\u5b58\u50a8\u5f15\u64ce MyISAM \u548c InnoDB\uff0c\u6bcf\u4e2a\u5f15\u64ce\u90fd\u6709\u5229\u6709\u5f0a\u3002\u9177\u58f3\u4ee5\u524d\u6587\u7ae0\u300aMySQL: InnoDB \u8fd8\u662f MyISAM?<\/a>\u300b\u8ba8\u8bba\u548c\u8fd9\u4e2a\u4e8b\u60c5\u3002<\/p>\n
MyISAM \u9002\u5408\u4e8e\u4e00\u4e9b\u9700\u8981\u5927\u91cf\u67e5\u8be2\u7684\u5e94\u7528\uff0c\u4f46\u5176\u5bf9\u4e8e\u6709\u5927\u91cf\u5199\u64cd\u4f5c\u5e76\u4e0d\u662f\u5f88\u597d\u3002\u751a\u81f3\u4f60\u53ea\u662f\u9700\u8981update\u4e00\u4e2a\u5b57\u6bb5\uff0c\u6574\u4e2a\u8868\u90fd\u4f1a\u88ab\u9501\u8d77\u6765\uff0c\u800c\u522b\u7684\u8fdb\u7a0b\uff0c\u5c31\u7b97\u662f\u8bfb\u8fdb\u7a0b\u90fd\u65e0\u6cd5\u64cd\u4f5c\u76f4\u5230\u8bfb\u64cd\u4f5c\u5b8c\u6210\u3002\u53e6\u5916\uff0cMyISAM \u5bf9\u4e8e SELECT COUNT(*) \u8fd9\u7c7b\u7684\u8ba1\u7b97\u662f\u8d85\u5feb\u65e0\u6bd4\u7684\u3002<\/p>\n
InnoDB \u7684\u8d8b\u52bf\u4f1a\u662f\u4e00\u4e2a\u975e\u5e38\u590d\u6742\u7684\u5b58\u50a8\u5f15\u64ce\uff0c\u5bf9\u4e8e\u4e00\u4e9b\u5c0f\u7684\u5e94\u7528\uff0c\u5b83\u4f1a\u6bd4 MyISAM \u8fd8\u6162\u3002\u4ed6\u662f\u5b83\u652f\u6301\u201c\u884c\u9501\u201d \uff0c\u4e8e\u662f\u5728\u5199\u64cd\u4f5c\u6bd4\u8f83\u591a\u7684\u65f6\u5019\uff0c\u4f1a\u66f4\u4f18\u79c0\u3002\u5e76\u4e14\uff0c\u4ed6\u8fd8\u652f\u6301\u66f4\u591a\u7684\u9ad8\u7ea7\u5e94\u7528\uff0c\u6bd4\u5982\uff1a\u4e8b\u52a1\u3002<\/p>\n
\u4e0b\u9762\u662fMySQL\u7684\u624b\u518c<\/p>\n