\u786e\u5b9a\u6570\u636e\u5b58\u653e\u4f4d\u7f6e\u548c\u5b58\u50a8\u7ed3\u6784\u9700\u8981\u8003\u8651\u7684\u56e0\u7d20\u4e3b\u8981\u6709\uff1a \u5b58\u53d6\u65f6\u95f4\u3001 \u5b58\u50a8\u7a7a\u95f4\u5229\u7528\u7387\u548c\u7ef4\u62a4\u4ee3\u4ef7\u7b49\u3002
\u4e8c\u3001\u7ec6\u8bf4\u6570\u636e\u5e93\u4e09\u8303\u5f0f
2.1 \u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u65e0\u91cd\u590d\u7684\u5217
\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u4e2d\u6570\u636e\u5e93\u8868\u7684\u6bcf\u4e00\u5217\u90fd\u662f\u4e0d\u53ef\u5206\u5272\u7684\u57fa\u672c\u6570\u636e\u9879
\u540c\u4e00\u5217\u4e2d\u4e0d\u80fd\u6709\u591a\u4e2a\u503c
\u5373\u5b9e\u4f53\u4e2d\u7684\u67d0\u4e2a\u5c5e\u6027\u4e0d\u80fd\u6709\u591a\u4e2a\u503c\u6216\u8005\u4e0d\u80fd\u6709\u91cd\u590d\u7684\u5c5e\u6027\u3002
\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e00\u8303\u5f0f\u5c31\u662f\u65e0\u91cd\u590d\u7684\u5217\u3002
\u5728\u4efb\u4f55\u4e00\u4e2a\u5173\u7cfb\u6570\u636e\u5e93\u4e2d\uff0c\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u662f\u5bf9\u5173\u7cfb\u6a21\u5f0f\u7684\u57fa\u672c\u8981\u6c42\uff0c\u4e0d\u6ee1\u8db3\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u7684\u6570\u636e\u5e93\u5c31\u4e0d\u662f\u5173\u7cfb\u6570\u636e\u5e93\u3002
2.2 \u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u5c5e\u6027\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u952e[\u6d88\u9664\u90e8\u5206\u5b50\u51fd\u6570\u4f9d\u8d56]
\u6ee1\u8db3\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u5fc5\u987b\u5148\u6ee1\u8db3\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u3002
\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u8981\u6c42\u6570\u636e\u5e93\u8868\u4e2d\u7684\u6bcf\u4e2a\u5b9e\u4f8b\u6216\u884c\u5fc5\u987b\u53ef\u4ee5\u88ab\u60df\u4e00\u5730\u533a\u5206\u3002
\u4e3a\u5b9e\u73b0\u533a\u5206\u901a\u5e38\u9700\u8981\u4e3a\u8868\u52a0\u4e0a\u4e00\u4e2a\u5217\uff0c\u4ee5\u5b58\u50a8\u5404\u4e2a\u5b9e\u4f8b\u7684\u60df\u4e00\u6807\u8bc6\u3002
\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u8981\u6c42\u5b9e\u4f53\u7684\u5c5e\u6027\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u5173\u952e\u5b57\u3002\u6240\u8c13\u5b8c\u5168\u4f9d\u8d56\u662f\u6307\u4e0d\u80fd\u5b58\u5728\u4ec5\u4f9d\u8d56\u4e3b\u5173\u952e\u5b57\u4e00\u90e8\u5206\u7684\u5c5e\u6027\uff0c\u5982\u679c\u5b58\u5728\uff0c\u90a3\u4e48\u8fd9\u4e2a\u5c5e
\u6027\u548c\u4e3b\u5173\u952e\u5b57\u7684\u8fd9\u4e00\u90e8\u5206\u5e94\u8be5\u5206\u79bb\u51fa\u6765\u5f62\u6210\u4e00\u4e2a\u65b0\u7684\u5b9e\u4f53\uff0c\u65b0\u5b9e\u4f53\u4e0e\u539f\u5b9e\u4f53\u4e4b\u95f4\u662f\u4e00\u5bf9\u591a\u7684\u5173\u7cfb\u3002\u4e3a\u5b9e\u73b0\u533a\u5206\u901a\u5e38\u9700\u8981\u4e3a\u8868\u52a0\u4e0a\u4e00\u4e2a\u5217\uff0c\u4ee5\u5b58
\u50a8\u5404\u4e2a\u5b9e\u4f8b\u7684\u60df\u4e00\u6807\u8bc6\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e8c\u8303\u5f0f\u5c31\u662f\u5c5e\u6027\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u952e\u3002
2.3 \u7b2c\u4e09\u8303\u5f0f\uff083NF\uff09\u5c5e\u6027\u4e0d\u4f9d\u8d56\u4e8e\u5176\u5b83\u975e\u4e3b\u5c5e\u6027[\u6d88\u9664\u4f20\u9012\u4f9d\u8d56]
\u6ee1\u8db3\u7b2c\u4e09\u8303\u5f0f\uff083NF\uff09\u5fc5\u987b\u5148\u6ee1\u8db3\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u3002
\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e09\u8303\u5f0f\uff083NF\uff09\u8981\u6c42\u4e00\u4e2a\u6570\u636e\u5e93\u8868\u4e2d\u4e0d\u5305\u542b\u5df2\u5728\u5176\u5b83\u8868\u4e2d\u5df2\u5305\u542b\u7684\u975e\u4e3b\u5173\u952e\u5b57\u4fe1\u606f\u3002
\u4f8b\u5982\uff0c\u5b58\u5728\u4e00\u4e2a\u90e8\u95e8\u4fe1\u606f\u8868\uff0c\u5176\u4e2d\u6bcf\u4e2a\u90e8\u95e8\u6709\u90e8\u95e8\u7f16\u53f7\uff08dept_id\uff09\u3001\u90e8\u95e8\u540d\u79f0\u3001\u90e8\u95e8\u7b80\u4ecb\u7b49\u4fe1\u606f\u3002\u90a3\u4e48\u5728\u7684\u5458\u5de5\u4fe1\u606f\u8868\u4e2d\u5217\u51fa\u90e8\u95e8\u7f16\u53f7\u540e\u5c31
\u4e0d\u80fd\u518d\u5c06\u90e8\u95e8\u540d\u79f0\u3001\u90e8\u95e8\u7b80\u4ecb\u7b49\u4e0e\u90e8\u95e8\u6709\u5173\u7684\u4fe1\u606f\u518d\u52a0\u5165\u5458\u5de5\u4fe1\u606f\u8868\u4e2d\u3002\u5982\u679c\u4e0d\u5b58\u5728\u90e8\u95e8\u4fe1\u606f\u8868\uff0c\u5219\u6839\u636e\u7b2c\u4e09\u8303\u5f0f\uff083NF\uff09\u4e5f\u5e94\u8be5\u6784\u5efa\u5b83\uff0c\u5426\u5219
\u5c31\u4f1a\u6709\u5927\u91cf\u7684\u6570\u636e\u5197\u4f59\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e09\u8303\u5f0f\u5c31\u662f\u5c5e\u6027\u4e0d\u4f9d\u8d56\u4e8e\u5176\u5b83\u975e\u4e3b\u5c5e\u6027\u3002
2.4 \u5177\u4f53\u5b9e\u4f8b\u5256\u6790
\u4e0b\u9762\u5217\u4e3e\u4e00\u4e2a\u5b66\u6821\u7684\u5b66\u751f\u7cfb\u7edf\u7684\u5b9e\u4f8b\uff0c\u4ee5\u793a\u51e0\u4e2a\u8303\u5f0f\u7684\u5e94\u7528\u3002
\u5728\u8bbe\u8ba1\u6570\u636e\u5e93\u8868\u7ed3\u6784\u4e4b\u524d\uff0c\u6211\u4eec\u5148\u786e\u5b9a\u4e00\u4e0b\u8981\u8bbe\u8ba1\u7684\u5185\u5bb9\u5305\u62ec\u90a3\u4e9b\u3002\u5b66\u53f7\u3001\u5b66\u751f\u59d3\u540d\u3001\u5e74\u9f84\u3001\u6027\u522b\u3001\u8bfe\u7a0b\u3001\u8bfe\u7a0b\u5b66\u5206\u3001\u7cfb\u522b\u3001\u5b66\u79d1\u6210\u7ee9\uff0c
\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd\u7b49\u4fe1\u606f\u3002\u4e3a\u4e86\u7b80\u5355\u6211\u4eec\u6682\u65f6\u53ea\u8003\u8651\u8fd9\u4e9b\u5b57\u6bb5\u4fe1\u606f\u3002\u6211\u4eec\u5bf9\u4e8e\u8fd9\u4e9b\u4fe1\u606f\uff0c\u8bf4\u5173\u5fc3\u7684\u95ee\u9898\u6709\u5982\u4e0b\u51e0\u4e2a\u65b9\u9762\u3002
1\uff09\u5b66\u751f\u6709\u90a3\u4e9b\u57fa\u672c\u4fe1\u606f
2\uff09\u5b66\u751f\u9009\u4e86\u90a3\u4e9b\u8bfe\uff0c\u6210\u7ee9\u662f\u4ec0\u4e48
3\uff09\u6bcf\u4e2a\u8bfe\u7684\u5b66\u5206\u662f\u591a\u5c11
4\uff09\u5b66\u751f\u5c5e\u4e8e\u90a3\u4e2a\u7cfb\uff0c\u7cfb\u7684\u57fa\u672c\u4fe1\u606f\u662f\u4ec0\u4e48\u3002
\u9996\u5148\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\uff1a\u6570\u636e\u5e93\u8868\u4e2d\u7684\u5b57\u6bb5\u90fd\u662f\u5355\u4e00\u5c5e\u6027\u7684\uff0c\u4e0d\u53ef\u518d\u5206\u3002\u8fd9\u4e2a\u5355\u4e00\u5c5e\u6027\u7531\u57fa\u672c\u7c7b\u578b\u6784\u6210\uff0c\u5305\u62ec\u6574\u578b\u3001\u5b9e\u6570\u3001\u5b57\u7b26\u578b\u3001\u903b\u8f91
\u578b\u3001\u65e5\u671f\u578b\u7b49\u3002\u5728\u5f53\u524d\u7684\u4efb\u4f55\u5173\u7cfb\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\uff08DBMS\uff09\u4e2d\uff0c\u4e0d\u5141\u8bb8\u4f60\u628a\u6570\u636e\u5e93\u8868\u7684\u4e00\u5217\u518d\u5206\u6210\u4e8c\u5217\u6216\u591a\u5217\uff0c\u56e0\u6b64\u505a\u51fa\u7684\u90fd\u662f\u7b26\u5408\u7b2c\u4e00\u8303\u5f0f
\u7684\u6570\u636e\u5e93\u3002
\u6211\u4eec\u518d\u8003\u8651\u7b2c\u4e8c\u8303\u5f0f\uff0c\u628a\u6240\u6709\u8fd9\u4e9b\u4fe1\u606f\u653e\u5230\u4e00\u4e2a\u8868\u4e2d(\u5b66\u53f7\uff0c\u5b66\u751f\u59d3\u540d\u3001\u5e74\u9f84\u3001\u6027\u522b\u3001\u8bfe\u7a0b\u3001\u8bfe\u7a0b\u5b66\u5206\u3001\u7cfb\u522b\u3001\u5b66\u79d1\u6210\u7ee9\uff0c\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e
\u7535\u8bdd)\u4e0b\u9762\u5b58\u5728\u5982\u4e0b\u7684\u4f9d\u8d56\u5173\u7cfb\u3002
1\uff09\uff08\u5b66\u53f7\uff09\u2192 (\u59d3\u540d, \u5e74\u9f84\uff0c\u6027\u522b\uff0c\u7cfb\u522b\uff0c\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd)
2\uff09 (\u8bfe\u7a0b\u540d\u79f0) \u2192 (\u5b66\u5206)
3\uff09\uff08\u5b66\u53f7\uff0c\u8bfe\u7a0b\uff09\u2192 (\u5b66\u79d1\u6210\u7ee9)
\u6839\u636e\u4f9d\u8d56\u5173\u7cfb\u6211\u4eec\u53ef\u4ee5\u628a\u9009\u8bfe\u5173\u7cfb\u8868SelectCourse\u6539\u4e3a\u5982\u4e0b\u4e09\u4e2a\u8868\uff1a
\u5b66\u751f\uff1aStudent(\u5b66\u53f7\uff0c\u59d3\u540d, \u5e74\u9f84\uff0c\u6027\u522b\uff0c\u7cfb\u522b\uff0c\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd)\uff1b
\u8bfe\u7a0b\uff1aCourse(\u8bfe\u7a0b\u540d\u79f0, \u5b66\u5206)\uff1b
\u9009\u8bfe\u5173\u7cfb\uff1aSelectCourse(\u5b66\u53f7, \u8bfe\u7a0b\u540d\u79f0, \u6210\u7ee9)\u3002
\u4e8b\u5b9e\u4e0a\uff0c\u5bf9\u7167\u7b2c\u4e8c\u8303\u5f0f\u7684\u8981\u6c42\uff0c\u8fd9\u5c31\u662f\u6ee1\u8db3\u7b2c\u4e8c\u8303\u5f0f\u7684\u6570\u636e\u5e93\u8868\uff0c\u82e5\u4e0d\u6ee1\u8db3\u7b2c\u4e8c\u8303\u5f0f\uff0c\u4f1a\u4ea7\u751f\u5982\u4e0b\u95ee\u9898
\u6570\u636e\u5197\u4f59\uff1a \u540c\u4e00\u95e8\u8bfe\u7a0b\u7531n\u4e2a\u5b66\u751f\u9009\u4fee\uff0c\"\u5b66\u5206\"\u5c31\u91cd\u590dn-1\u6b21\uff1b\u540c\u4e00\u4e2a\u5b66\u751f\u9009\u4fee\u4e86m\u95e8\u8bfe\u7a0b\uff0c\u59d3\u540d\u548c\u5e74\u9f84\u5c31\u91cd\u590d\u4e86m-1\u6b21\u3002
\u66f4\u65b0\u5f02\u5e38\uff1a 1)\u82e5\u8c03\u6574\u4e86\u67d0\u95e8\u8bfe\u7a0b\u7684\u5b66\u5206\uff0c\u6570\u636e\u8868\u4e2d\u6240\u6709\u884c\u7684\"\u5b66\u5206\"\u503c\u90fd\u8981\u66f4\u65b0\uff0c\u5426\u5219\u4f1a\u51fa\u73b0\u540c\u4e00\u95e8\u8bfe\u7a0b\u5b66\u5206\u4e0d\u540c\u7684\u60c5\u51b5\u3002
2)\u5047\u8bbe\u8981\u5f00\u8bbe\u4e00\u95e8\u65b0\u7684\u8bfe\u7a0b\uff0c\u6682\u65f6\u8fd8\u6ca1\u6709\u4eba\u9009\u4fee\u3002\u8fd9\u6837\uff0c\u7531\u4e8e\u8fd8\u6ca1\u6709\"\u5b66\u53f7\"\u5173\u952e\u5b57\uff0c\u8bfe\u7a0b\u540d\u79f0\u548c\u5b66\u5206\u4e5f\u65e0\u6cd5\u8bb0\u5f55\u5165\u6570\u636e\u5e93\u3002
\u5220\u9664\u5f02\u5e38 \uff1a \u5047\u8bbe\u4e00\u6279\u5b66\u751f\u5df2\u7ecf\u5b8c\u6210\u8bfe\u7a0b\u7684\u9009\u4fee\uff0c\u8fd9\u4e9b\u9009\u4fee\u8bb0\u5f55\u5c31\u5e94\u8be5\u4ece\u6570\u636e\u5e93\u8868\u4e2d\u5220\u9664\u3002\u4f46\u662f\uff0c\u4e0e\u6b64\u540c\u65f6\uff0c\u8bfe\u7a0b\u540d\u79f0\u548c\u5b66\u5206\u4fe1\u606f\u4e5f\u88ab\u5220\u9664\u4e86\u3002
\u5f88\u663e\u7136\uff0c\u8fd9\u4e5f\u4f1a\u5bfc\u81f4\u63d2\u5165\u5f02\u5e38\u3002
\u6211\u4eec\u518d\u8003\u8651\u5982\u4f55\u5c06\u5176\u6539\u6210\u6ee1\u8db3\u7b2c\u4e09\u8303\u5f0f\u7684\u6570\u636e\u5e93\u8868\uff0c\u63a5\u7740\u770b\u4e0a\u9762\u7684\u5b66\u751f\u8868Student(\u5b66\u53f7\uff0c\u59d3\u540d, \u5e74\u9f84\uff0c\u6027\u522b\uff0c\u7cfb\u522b\uff0c\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd)\uff0c
\u5173\u952e\u5b57\u4e3a\u5355\u4e00\u5173\u952e\u5b57\"\u5b66\u53f7\"\uff0c\u56e0\u4e3a\u5b58\u5728\u5982\u4e0b\u51b3\u5b9a\u5173\u7cfb\uff1a
\uff08\u5b66\u53f7\uff09\u2192 (\u59d3\u540d, \u5e74\u9f84\uff0c\u6027\u522b\uff0c\u7cfb\u522b\uff0c\u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd)
\u4f46\u662f\u8fd8\u5b58\u5728\u4e0b\u9762\u7684\u51b3\u5b9a\u5173\u7cfb
(\u5b66\u53f7) \u2192 (\u6240\u5728\u5b66\u9662)\u2192(\u5b66\u9662\u5730\u70b9, \u5b66\u9662\u7535\u8bdd)
\u5373\u5b58\u5728\u975e\u5173\u952e\u5b57\u6bb5\"\u5b66\u9662\u5730\u70b9\"\u3001\"\u5b66\u9662\u7535\u8bdd\"\u5bf9\u5173\u952e\u5b57\u6bb5\"\u5b66\u53f7\"\u7684\u4f20\u9012\u51fd\u6570\u4f9d\u8d56\u3002
\u5b83\u4e5f\u4f1a\u5b58\u5728\u6570\u636e\u5197\u4f59\u3001\u66f4\u65b0\u5f02\u5e38\u3001\u63d2\u5165\u5f02\u5e38\u548c\u5220\u9664\u5f02\u5e38\u7684\u60c5\u51b5\uff08\u8fd9\u91cc\u5c31\u4e0d\u5177\u4f53\u5206\u6790\u4e86\uff0c\u53c2\u7167\u7b2c\u4e8c\u8303\u5f0f\u4e2d\u7684\u5206\u6790\uff09\u3002\u6839\u636e\u7b2c\u4e09\u8303\u5f0f\u628a\u5b66\u751f\u5173
\u7cfb\u8868\u5206\u4e3a\u5982\u4e0b\u4e24\u4e2a\u8868\u5c31\u53ef\u4ee5\u6ee1\u8db3\u7b2c\u4e09\u8303\u5f0f\u4e86\uff1a
\u5b66\u751f\uff1a(\u5b66\u53f7, \u59d3\u540d, \u5e74\u9f84, \u6027\u522b\uff0c\u7cfb\u522b)\uff1b
\u7cfb\u522b\uff1a(\u7cfb\u522b, \u7cfb\u529e\u5730\u5740\u3001\u7cfb\u529e\u7535\u8bdd)\u3002
SQL\u8bed\u53e5\u603b\u7ed3
SQL\u8bed\u53e5\u4e2d\u5e38\u7528\u5173\u952e\u8bcd\u53ca\u5176\u89e3\u91ca\u5982\u4e0b\uff1a
1\uff09SELECT
\u5c06\u8d44\u6599\u4ece\u6570\u636e\u5e93\u4e2d\u7684\u8868\u683c\u5185\u9009\u51fa\uff0c\u4e24\u4e2a\u5173\u952e\u5b57\uff1a\u4ece (FROM) \u6570\u636e\u5e93\u4e2d\u7684\u8868\u683c\u5185\u9009\u51fa (SELECT)\u3002\u8bed\u6cd5\u4e3a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\"\u3002
2\uff09DISTINCT
\u5728\u4e0a\u8ff0 SELECT \u5173\u952e\u8bcd\u540e\u52a0\u4e0a\u4e00\u4e2a DISTINCT \u5c31\u53ef\u4ee5\u53bb\u9664\u9009\u62e9\u51fa\u6765\u7684\u680f\u4f4d\u4e2d\u7684\u91cd\u590d\uff0c\u4ece\u800c\u5b8c\u6210\u6c42\u5f97\u8fd9\u4e2a\u8868\u683c\/\u680f\u4f4d\u5185\u6709\u54ea\u4e9b\u4e0d\u540c\u7684\u503c\u7684\u529f\u80fd\u3002\u8bed
\u6cd5\u4e3a
SELECT DISTINCT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\"\u3002
3\uff09WHERE
\u8fd9\u4e2a\u5173\u952e\u8bcd\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u9009\u62e9\u6027\u5730\u6293\u8d44\u6599\uff0c\u800c\u4e0d\u662f\u5168\u53d6\u51fa\u6765\u3002\u8bed\u6cd5\u4e3a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\" WHERE \"\u6761\u4ef6\"
4\uff09AND OR
\u4e0a\u4f8b\u4e2d\u7684 WHERE \u6307\u4ee4\u53ef\u4ee5\u88ab\u7528\u6765\u7531\u8868\u683c\u4e2d\u6709\u6761\u4ef6\u5730\u9009\u53d6\u8d44\u6599\u3002\u8fd9\u4e2a\u6761\u4ef6\u53ef\u80fd\u662f\u7b80\u5355\u7684 (\u50cf\u4e0a\u4e00\u9875\u7684\u4f8b\u5b50)\uff0c\u4e5f\u53ef\u80fd\u662f\u590d\u6742\u7684\u3002\u590d\u6742\u6761\u4ef6\u662f\u7531\u4e8c
\u6216\u591a\u4e2a\u7b80\u5355\u6761\u4ef6\u900f\u8fc7 AND \u6216\u662f OR \u7684\u8fde\u63a5\u800c\u6210\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\" WHERE \"\u7b80\u5355\u6761\u4ef6\" {[AND|OR] \"\u7b80\u5355\u6761\u4ef6\"}+
5\uff09IN
\u5728 SQL \u4e2d\uff0c\u5728\u4e24\u4e2a\u60c5\u51b5\u4e0b\u4f1a\u7528\u5230 IN \u8fd9\u4e2a\u6307\u4ee4\uff1b\u8fd9\u4e00\u9875\u5c06\u4ecb\u7ecd\u5176\u4e2d\u4e4b\u4e00\uff1a\u4e0e WHERE \u6709\u5173\u7684\u90a3\u4e00\u4e2a\u60c5\u51b5\u3002\u5728\u8fd9\u4e2a\u7528\u6cd5\u4e0b\uff0c\u6211\u4eec\u4e8b\u5148\u5df2\u77e5\u9053\u81f3\u5c11
\u4e00\u4e2a\u6211\u4eec\u9700\u8981\u7684\u503c\uff0c\u800c\u6211\u4eec\u5c06\u8fd9\u4e9b\u77e5\u9053\u7684\u503c\u90fd\u653e\u5165 IN \u8fd9\u4e2a\u5b50\u53e5\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\" WHERE \"\u680f\u4f4d\u540d\" IN ('\u503c\u4e00', '\u503c\u4e8c', \u2026)
6\uff09BETWEEN
IN \u8fd9\u4e2a\u6307\u4ee4\u53ef\u4ee5\u8ba9\u6211\u4eec\u4f9d\u7167\u4e00\u6216\u6570\u4e2a\u4e0d\u8fde\u7eed (discrete)\u7684\u503c\u7684\u9650\u5236\u4e4b\u5185\u6293\u51fa\u8d44\u6599\u5e93\u4e2d\u7684\u503c\uff0c\u800c BETWEEN \u5219\u662f\u8ba9\u6211\u4eec\u53ef\u4ee5\u8fd0\u7528\u4e00\u4e2a\u8303\u56f4 (range)
\u5185\u6293\u51fa\u8d44\u6599\u5e93\u4e2d\u7684\u503c\uff0c\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\" WHERE \"\u680f\u4f4d\u540d\" BETWEEN '\u503c\u4e00' AND '\u503c\u4e8c'
7\uff09LIKE
LIKE \u662f\u53e6\u4e00\u4e2a\u5728 WHERE \u5b50\u53e5\u4e2d\u4f1a\u7528\u5230\u7684\u6307\u4ee4\u3002\u57fa\u672c\u4e0a\uff0c LIKE \u80fd\u8ba9\u6211\u4eec\u4f9d\u636e\u4e00\u4e2a\u6a21\u5f0f(pattern) \u6765\u627e\u51fa\u6211\u4eec\u8981\u7684\u8d44\u6599\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d\" WHERE \"\u680f\u4f4d\u540d\" LIKE {\u6a21\u5f0f}
8\uff09ORDER BY
\u6211\u4eec\u7ecf\u5e38\u9700\u8981\u80fd\u591f\u5c06\u6293\u51fa\u7684\u8d44\u6599\u505a\u4e00\u4e2a\u6709\u7cfb\u7edf\u7684\u663e\u793a\u3002\u8fd9\u53ef\u80fd\u662f\u7531\u5c0f\u5f80\u5927 (ascending) \u6216\u662f\u7531\u5927\u5f80\u5c0f(descending)\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u8fd0
\u7528 ORDER BY \u8fd9\u4e2a\u6307\u4ee4\u6765\u8fbe\u5230\u6211\u4eec\u7684\u76ee\u7684\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d\u540d\" FROM \"\u8868\u683c\u540d [WHERE \"\u6761\u4ef6\"] ORDER BY \"\u680f\u4f4d\u540d\" [ASC, DESC]
9\uff09\u51fd\u6570
\u51fd\u6570\u5141\u8bb8\u6211\u4eec\u80fd\u591f\u5bf9\u8fd9\u4e9b\u6570\u5b57\u7684\u578b\u6001\u5b58\u5728\u7684\u884c\u6216\u8005\u5217\u505a\u8fd0\u7b97\uff0c\u5305\u62ec AVG (\u5e73\u5747)\u3001COUNT (\u8ba1\u6570)\u3001MAX (\u6700\u5927\u503c)\u3001MIN (\u6700\u5c0f\u503c)\u3001SUM (\u603b\u5408)\u3002
\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u51fd\u6570\u540d\"(\"\u680f\u4f4d\u540d\") FROM \"\u8868\u683c\u540d\"
10\uff09COUNT
\u8fd9\u4e2a\u5173\u952e\u8bcd\u80fd\u591f\u5e2e\u6211\u6211\u4eec\u7edf\u8ba1\u6709\u591a\u5c11\u7b14\u8d44\u6599\u88ab\u9009\u51fa\u6765\uff0c\u8bed\u6cd5\u4e3a\uff1a
SELECT COUNT(\"\u680f\u4f4d\u540d\") FROM \"\u8868\u683c\u540d\"
11\uff09GROUP BY
GROUP BY \u8bed\u53e5\u7528\u4e8e\u7ed3\u5408\u5408\u8ba1\u51fd\u6570\uff0c\u6839\u636e\u4e00\u4e2a\u6216\u591a\u4e2a\u5217\u5bf9\u7ed3\u679c\u96c6\u8fdb\u884c\u5206\u7ec4\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d1\", SUM(\"\u680f\u4f4d2\") FROM \"\u8868\u683c\u540d\" GROUP BY \"\u680f\u4f4d1\"
12\uff09HAVING
\u8be5\u5173\u952e\u8bcd\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u5bf9\u51fd\u6570\u4ea7\u751f\u7684\u503c\u6765\u8bbe\u5b9a\u6761\u4ef6\u3002\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u680f\u4f4d1\", SUM(\"\u680f\u4f4d2\") FROM \"\u8868\u683c\u540d\" GROUP BY \"\u680f\u4f4d1\" HAVING (\u51fd\u6570\u6761\u4ef6)
13\uff09ALIAS
\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7ALIAS\u4e3a\u5217\u540d\u79f0\u548c\u8868\u540d\u79f0\u6307\u5b9a\u522b\u540d\uff0c\u8bed\u6cd5\u4e3a\uff1a
SELECT \"\u8868\u683c\u522b\u540d\".\"\u680f\u4f4d1\" \"\u680f\u4f4d\u522b\u540d\" FROM \"\u8868\u683c\u540d\" \"\u8868\u683c\u522b\u540d\"
\u4e0b\u9762\u4e3a\u4e00\u4e2a\u4f8b\u5b50\uff0c\u901a\u8fc7\u5b83\u6211\u4eec\u5e94\u8be5\u80fd\u5f88\u597d\u5730\u638c\u63e1\u4ee5\u4e0a\u5173\u952e\u8bcd\u7684\u4f7f\u7528\u65b9\u6cd5\u3002
Student(S#,Sname,Sage,Ssex) \u5b66\u751f\u8868
Course(C#,Cname,T#) \u8bfe\u7a0b\u8868
SC(S#,C#,score) \u6210\u7ee9\u8868
Teacher(T#,Tname) \u6559\u5e08\u8868
\u95ee\u9898\uff1a
1\u3001\u67e5\u8be2\u201c001\u201d\u8bfe\u7a0b\u6bd4\u201c002\u201d\u8bfe\u7a0b\u6210\u7ee9\u9ad8\u7684\u6240\u6709\u5b66\u751f\u7684\u5b66\u53f7\uff1b
select a.S#
from (select s#,score from SC where C#=\u2019001\u2032) a,
(select s#,score from SC where C#=\u2019002\u2032) b
where a.score>b.score and a.s#=b.s#;
2\u3001\u67e5\u8be2\u5e73\u5747\u6210\u7ee9\u5927\u4e8e60\u5206\u7684\u540c\u5b66\u7684\u5b66\u53f7\u548c\u5e73\u5747\u6210\u7ee9\uff1b
select S#,avg(score)
from sc
group by S# having avg(score) >60;
3\u3001\u67e5\u8be2\u6240\u6709\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\u3001\u9009\u8bfe\u6570\u3001\u603b\u6210\u7ee9\uff1b
select Student.S#,Student.Sname,count(SC.C#),sum(score)
from Student left Outer join SC on Student.S#=SC.S#
group by Student.S#,Sname
4\u3001\u67e5\u8be2\u59d3\u201c\u674e\u201d\u7684\u8001\u5e08\u7684\u4e2a\u6570\uff1b
select count(distinct(Tname))
from Teacher
where Tname like \u2018\u674e%\u2019;
5\u3001\u67e5\u8be2\u6ca1\u5b66\u8fc7\u201c\u53f6\u5e73\u201d\u8001\u5e08\u8bfe\u7684\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\uff1b
select Student.S#,Student.Sname
from Student
where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=\u2019\u53f6\u5e73\u2019);
6\u3001\u67e5\u8be2\u5b66\u8fc7\u201c001\u201d\u5e76\u4e14\u4e5f\u5b66\u8fc7\u7f16\u53f7\u201c002\u201d\u8bfe\u7a0b\u7684\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\uff1b
select Student.S#,Student.Sname
from Student,SC
where Student.S#=SC.S# and SC.C#=\u2019001\u2032and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#=\u2019002\u2032);
7\u3001\u67e5\u8be2\u5b66\u8fc7\u201c\u53f6\u5e73\u201d\u8001\u5e08\u6240\u6559\u7684\u6240\u6709\u8bfe\u7684\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\uff1b
select S#,Sname
from Student
where S# in
(select S#
from SC ,Course ,Teacher
where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=\u2019\u53f6\u5e73\u2019 group by S# having count(SC.C#)=(select count(C#) from
Course,Teacher where Teacher.T#=Course.T# and Tname=\u2019\u53f6\u5e73\u2019));
8\u3001\u67e5\u8be2\u6240\u6709\u8bfe\u7a0b\u6210\u7ee9\u5c0f\u4e8e60\u5206\u7684\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\uff1b
select S#,Sname
from Student
where S# not in (select Student.S# from Student,SC where S.S#=SC.S# and score>60);
9\u3001\u67e5\u8be2\u6ca1\u6709\u5b66\u5168\u6240\u6709\u8bfe\u7684\u540c\u5b66\u7684\u5b66\u53f7\u3001\u59d3\u540d\uff1b
select Student.S#,Student.Sname
from Student,SC
where Student.S#=SC.S#
group by Student.S#,Student.Sname having count(C#) <(select count(C#) from Course); 10\u3001\u67e5\u8be2\u81f3\u5c11\u6709\u4e00\u95e8\u8bfe\u4e0e\u5b66\u53f7\u4e3a\u201c1001\u201d\u7684\u540c\u5b66\u6240\u5b66\u76f8\u540c\u7684\u540c\u5b66\u7684\u5b66\u53f7\u548c\u59d3\u540d\uff1b select S#,Sname from Student,SC where Student.S#=SC.S# and C# in \uff08select C# from SC where S#='1001'\uff09; 11\u3001\u5220\u9664\u5b66\u4e60\u201c\u53f6\u5e73\u201d\u8001\u5e08\u8bfe\u7684SC\u8868\u8bb0\u5f55\uff1b Delect SC from course ,Teacher where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname='\u53f6\u5e73'; 12\u3001\u67e5\u8be2\u5404\u79d1\u6210\u7ee9\u6700\u9ad8\u548c\u6700\u4f4e\u7684\u5206\uff1a\u4ee5\u5982\u4e0b\u5f62\u5f0f\u663e\u793a\uff1a\u8bfe\u7a0bID\uff0c\u6700\u9ad8\u5206\uff0c\u6700\u4f4e\u5206 SELECT L.C# \u8bfe\u7a0bID,L.score \u6700\u9ad8\u5206,R.score \u6700\u4f4e\u5206 FROM SC L ,SC R WHERE L.C# = R.C# and L.score = (SELECT MAX(IL.score) FROM SC IL,Student IM WHERE IL.C# = L.C# and IM.S#=IL.S# GROUP BY IL.C#) and R.Score = (SELECT MIN(IR.score) FROM SC IR WHERE IR.C# = R.C# GROUP BY IR.C# ); 13\u3001\u67e5\u8be2\u5b66\u751f\u5e73\u5747\u6210\u7ee9\u53ca\u5176\u540d\u6b21 SELECT 1+(SELECT COUNT( distinct \u5e73\u5747\u6210\u7ee9) FROM (SELECT S#,AVG(score) \u5e73\u5747\u6210\u7ee9 FROM SC GROUP BY S# ) T1 WHERE \u5e73\u5747\u6210\u7ee9 > T2.\u5e73\u5747\u6210\u7ee9) \u540d\u6b21, S# \u5b66\u751f\u5b66\u53f7,\u5e73\u5747\u6210\u7ee9
FROM (SELECT S#,AVG(score) \u5e73\u5747\u6210\u7ee9 FROM SC GROUP BY S# ) T2
ORDER BY \u5e73\u5747\u6210\u7ee9 desc;
14\u3001\u67e5\u8be2\u5404\u79d1\u6210\u7ee9\u524d\u4e09\u540d\u7684\u8bb0\u5f55:(\u4e0d\u8003\u8651\u6210\u7ee9\u5e76\u5217\u60c5\u51b5)
SELECT t1.S# as \u5b66\u751fID,t1.C# as \u8bfe\u7a0bID,Score as \u5206\u6570
FROM SC t1
WHERE score IN (SELECT TOP 3 score
FROM SC
WHERE t1.C#= C#
ORDER BY score DESC)
ORDER BY t1.C#;
15\u3001\u67e5\u8be2\u6bcf\u95e8\u529f\u6210\u7ee9\u6700\u597d\u7684\u524d\u4e24\u540d
SELECT t1.S# as \u5b66\u751fID,t1.C# as \u8bfe\u7a0bID,Score as \u5206\u6570
FROM SC t1
WHERE score IN (SELECT TOP 2 score
FROM SC
WHERE t1.C#= C#
ORDER BY score DESC )
ORDER BY t1.C#;<\/li>\n<\/ol>\n\n\n\n<\/p>\n","protected":false},"excerpt":{"rendered":"
\u7b2c\u4e00\u8282\u4e00\u3001\u76f8\u5173\u6982\u5ff5<\/p>\n","protected":false},"author":20615,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_locale":"en_US","_original_post":"https:\/\/zd1269878.noblogs.org\/?p=211","activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":4,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"federated","footnotes":""},"categories":[15],"tags":[16],"class_list":["post-211","post","type-post","status-publish","format-standard","hentry","category-15","tag-16","en-US"],"_links":{"self":[{"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/posts\/211","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/users\/20615"}],"replies":[{"embeddable":true,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/comments?post=211"}],"version-history":[{"count":2,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/posts\/211\/revisions"}],"predecessor-version":[{"id":291,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/posts\/211\/revisions\/291"}],"wp:attachment":[{"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/media?parent=211"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/categories?post=211"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zd1269878.noblogs.org\/wp-json\/wp\/v2\/tags?post=211"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}