{"id":2240,"date":"2023-06-27T15:33:03","date_gmt":"2023-06-27T07:33:03","guid":{"rendered":"https:\/\/xinchewhd.com.cn\/?p=2240"},"modified":"2023-06-27T15:33:03","modified_gmt":"2023-06-27T07:33:03","slug":"52%e6%9d%a1sql%e8%af%ad%e5%8f%a5%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e7%ad%96%e7%95%a5%ef%bc%8c%e5%bb%ba%e8%ae%ae%e6%94%b6%e8%97%8f","status":"publish","type":"post","link":"https:\/\/xinchewhd.com.cn\/index.php\/mysql\/52%e6%9d%a1sql%e8%af%ad%e5%8f%a5%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e7%ad%96%e7%95%a5%ef%bc%8c%e5%bb%ba%e8%ae%ae%e6%94%b6%e8%97%8f\/","title":{"rendered":"52\u6761SQL\u8bed\u53e5\u6027\u80fd\u4f18\u5316\u7b56\u7565\uff0c\u5efa\u8bae\u6536\u85cf"},"content":{"rendered":"
\n
<\/mp-common-profile><\/section>\n


<\/p>\n

\u672c\u6587\u4f1a\u63d0\u5230 52 \u6761 SQL \u8bed\u53e5\u6027\u80fd\u4f18\u5316\u7b56\u7565\u3002<\/span><\/p>\n


<\/p>\n

1\u3001\u5bf9\u67e5\u8be2\u8fdb\u884c\u4f18\u5316\uff0c\u5e94\u5c3d\u91cf\u907f\u514d\u5168\u8868\u626b\u63cf\uff0c\u9996\u5148\u5e94\u8003\u8651\u5728 WHERE \u53ca ORDER BY \u6d89\u53ca\u7684\u5217\u4e0a\u5efa\u7acb\u7d22\u5f15\u3002<\/span><\/p>\n


<\/p>\n

2\u3001\u5e94\u5c3d\u91cf\u907f\u514d\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u5bf9\u5b57\u6bb5\u8fdb\u884c NULL <\/span>\u503c\u5224\u65ad\uff0c\u521b\u5efa\u8868\u65f6 NULL \u662f\u9ed8\u8ba4\u503c\uff0c\u4f46\u5927\u591a\u6570\u65f6\u5019\u5e94\u8be5\u4f7f\u7528 NOT NULL\uff0c\u6216\u8005\u4f7f\u7528\u4e00\u4e2a\u7279\u6b8a\u7684\u503c\uff0c\u5982 0\uff0c-1 \u4f5c\u4e3a\u9ed8\u8ba4\u503c\u3002<\/span><\/p>\n


<\/p>\n

3\u3001\u5e94\u5c3d\u91cf\u907f\u514d\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u4f7f\u7528 != \u6216 <> \u64cd\u4f5c\u7b26\u3002MySQL \u53ea\u6709\u5bf9\u4ee5\u4e0b\u64cd\u4f5c\u7b26\u624d\u4f7f\u7528\u7d22\u5f15\uff1a<\uff0c<=\uff0c=\uff0c>\uff0c>=\uff0cBETWEEN\uff0cIN\uff0c\u4ee5\u53ca\u67d0\u4e9b\u65f6\u5019\u7684 LIKE\u3002<\/span><\/p>\n


<\/p>\n

4\u3001\u5e94\u5c3d\u91cf\u907f\u514d\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u4f7f\u7528 OR \u6765\u8fde\u63a5\u6761\u4ef6\uff0c\u5426\u5219\u5c06\u5bfc\u81f4\u5f15\u64ce\u653e\u5f03\u4f7f\u7528\u7d22\u5f15\u800c\u8fdb\u884c\u5168\u8868\u626b\u63cf\uff0c\u53ef\u4ee5\u4f7f\u7528 UNION \u5408\u5e76\u67e5\u8be2\uff1a<\/span>select id from t where num=10 union all select id from t where num=20<\/span>\u3002<\/span><\/p>\n


<\/p>\n

5\u3001IN \u548c NOT IN \u4e5f\u8981\u614e\u7528\uff0c\u5426\u5219\u4f1a\u5bfc\u81f4\u5168\u8868\u626b\u63cf\u3002\u5bf9\u4e8e\u8fde\u7eed\u7684\u6570\u503c\uff0c\u80fd\u7528 BETWEEN \u5c31\u4e0d\u8981\u7528 IN\uff1a<\/span>select id from t where num between 1 and 3<\/span>\u3002<\/span><\/p>\n


<\/p>\n

6\u3001\u4e0b\u9762\u7684\u67e5\u8be2\u4e5f\u5c06\u5bfc\u81f4\u5168\u8868\u626b\u63cf\uff1a<\/span>select id from t where name like\u2018%abc%\u2019 <\/span>\u6216\u8005select id from t where name like\u2018%abc\u2019\u82e5\u8981\u63d0\u9ad8\u6548\u7387\uff0c\u53ef\u4ee5\u8003\u8651\u5168\u6587\u68c0\u7d22\u3002\u800cselect id from t where name like\u2018abc%\u2019\u624d\u7528\u5230\u7d22\u5f15\u3002<\/span><\/p>\n


<\/p>\n

7\u3001\u5982\u679c\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u4f7f\u7528\u53c2\u6570\uff0c\u4e5f\u4f1a\u5bfc\u81f4\u5168\u8868\u626b\u63cf\u3002<\/span><\/p>\n


<\/p>\n

8\u3001\u5e94\u5c3d\u91cf\u907f\u514d\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u5bf9\u5b57\u6bb5\u8fdb\u884c\u8868\u8fbe\u5f0f\u64cd\u4f5c\uff0c\u5e94\u5c3d\u91cf\u907f\u514d\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\u5bf9\u5b57\u6bb5\u8fdb\u884c\u51fd\u6570\u64cd\u4f5c\u3002<\/span><\/p>\n


<\/p>\n

9\u3001\u5f88\u591a\u65f6\u5019\u7528 EXISTS \u4ee3\u66ff IN \u662f\u4e00\u4e2a\u597d\u7684\u9009\u62e9\uff1a<\/span>select num from a where num in(select num from b)<\/span>\u3002\u7528\u4e0b\u9762\u7684\u8bed\u53e5\u66ff\u6362\uff1a<\/span>select num from a where exists(select 1 from b where num=a.num)<\/span>\u3002<\/span><\/p>\n


<\/p>\n

10\u3001\u7d22\u5f15\u56fa\u7136\u53ef\u4ee5\u63d0\u9ad8\u76f8\u5e94\u7684 SELECT \u7684\u6548\u7387\uff0c\u4f46\u540c\u65f6\u4e5f\u964d\u4f4e\u4e86 INSERT \u53ca UPDATE \u7684\u6548\u3002\u56e0\u4e3a INSERT <\/span>\u6216 UPDATE <\/span>\u65f6\u6709\u53ef\u80fd\u4f1a\u91cd\u5efa\u7d22\u5f15\uff0c\u6240\u4ee5\u600e\u6837\u5efa\u7d22\u5f15\u9700\u8981\u614e\u91cd\u8003\u8651\uff0c\u89c6\u5177\u4f53\u60c5\u51b5\u800c\u5b9a\u3002\u4e00\u4e2a\u8868\u7684\u7d22\u5f15\u6570\u6700\u597d\u4e0d\u8981\u8d85\u8fc7 6 \u4e2a\uff0c\u82e5\u592a\u591a\u5219\u5e94\u8003\u8651\u4e00\u4e9b\u4e0d\u5e38\u4f7f\u7528\u5230\u7684\u5217\u4e0a\u5efa\u7684\u7d22\u5f15\u662f\u5426\u6709\u5fc5\u8981\u3002<\/span><\/p>\n


<\/p>\n

11\u3001\u5e94\u5c3d\u53ef\u80fd\u7684\u907f\u514d\u66f4\u65b0 clustered \u7d22\u5f15\u6570\u636e\u5217\uff0c \u56e0\u4e3a clustered \u7d22\u5f15\u6570\u636e\u5217\u7684\u987a\u5e8f\u5c31\u662f\u8868\u8bb0\u5f55\u7684\u7269\u7406\u5b58\u50a8\u987a\u5e8f\uff0c\u4e00\u65e6\u8be5\u5217\u503c\u6539\u53d8\u5c06\u5bfc\u81f4\u6574\u4e2a\u8868\u8bb0\u5f55\u7684\u987a\u5e8f\u7684\u8c03\u6574\uff0c\u4f1a\u8017\u8d39\u76f8\u5f53\u5927\u7684\u8d44\u6e90\u3002\u82e5\u5e94\u7528\u7cfb\u7edf\u9700\u8981\u9891\u7e41\u66f4\u65b0 clustered \u7d22\u5f15\u6570\u636e\u5217\uff0c\u90a3\u4e48\u9700\u8981\u8003\u8651\u662f\u5426\u5e94\u5c06\u8be5\u7d22\u5f15\u5efa\u4e3a clustered \u7d22\u5f15\u3002<\/span><\/p>\n


<\/p>\n

12\u3001\u5c3d\u91cf\u4f7f\u7528\u6570\u5b57\u578b\u5b57\u6bb5\uff0c\u82e5\u53ea\u542b\u6570\u503c\u4fe1\u606f\u7684\u5b57\u6bb5\u5c3d\u91cf\u4e0d\u8981\u8bbe\u8ba1\u4e3a\u5b57\u7b26\u578b\uff0c\u8fd9\u4f1a\u964d\u4f4e\u67e5\u8be2\u548c\u8fde\u63a5\u7684\u6027\u80fd\uff0c\u5e76\u4f1a\u589e\u52a0\u5b58\u50a8\u5f00\u9500\u3002<\/span><\/p>\n


<\/p>\n

13\u3001\u5c3d\u53ef\u80fd\u7684\u4f7f\u7528 varchar, nvarchar \u4ee3\u66ff char, nchar\u3002\u56e0\u4e3a\u9996\u5148\u53d8\u957f\u5b57\u6bb5\u5b58\u50a8\u7a7a\u95f4\u5c0f\uff0c\u53ef\u4ee5\u8282\u7701\u5b58\u50a8\u7a7a\u95f4\uff0c\u5176\u6b21\u5bf9\u4e8e\u67e5\u8be2\u6765\u8bf4\uff0c\u5728\u4e00\u4e2a\u76f8\u5bf9\u8f83\u5c0f\u7684\u5b57\u6bb5\u5185\u641c\u7d22\u6548\u7387\u663e\u7136\u8981\u9ad8\u4e9b\u3002<\/span><\/p>\n


<\/p>\n

14\u3001\u6700\u597d\u4e0d\u8981\u4f7f\u7528\u8fd4\u56de\u6240\u6709\uff1a<\/span>select from t <\/span>\uff0c\u7528\u5177\u4f53\u7684\u5b57\u6bb5\u5217\u8868\u4ee3\u66ff \u201c*\u201d\uff0c\u4e0d\u8981\u8fd4\u56de\u7528\u4e0d\u5230\u7684\u4efb\u4f55\u5b57\u6bb5\u3002<\/span><\/p>\n


<\/p>\n

15\u3001\u5c3d\u91cf\u907f\u514d\u5411\u5ba2\u6237\u7aef\u8fd4\u56de\u5927\u6570\u636e\u91cf\uff0c\u82e5\u6570\u636e\u91cf\u8fc7\u5927\uff0c\u5e94\u8be5\u8003\u8651\u76f8\u5e94\u9700\u6c42\u662f\u5426\u5408\u7406\u3002<\/span><\/p>\n


<\/p>\n

16\u3001\u4f7f\u7528\u8868\u7684\u522b\u540d\uff08Alias\uff09\uff1a\u5f53\u5728 SQL \u8bed\u53e5\u4e2d\u8fde\u63a5\u591a\u4e2a\u8868\u65f6\uff0c\u8bf7\u4f7f\u7528\u8868\u7684\u522b\u540d\u5e76\u628a\u522b\u540d\u524d\u7f00\u4e8e\u6bcf\u4e2a Column \u4e0a\u3002\u8fd9\u6837\u4e00\u6765\uff0c\u5c31\u53ef\u4ee5\u51cf\u5c11\u89e3\u6790\u7684\u65f6\u95f4\u5e76\u51cf\u5c11\u90a3\u4e9b\u7531 Column \u6b67\u4e49\u5f15\u8d77\u7684\u8bed\u6cd5\u9519\u8bef\u3002<\/span><\/p>\n


<\/p>\n

17\u3001\u4f7f\u7528\u201c\u4e34\u65f6\u8868\u201d\u6682\u5b58\u4e2d\u95f4\u7ed3\u679c \uff1a<\/span><\/p>\n


<\/p>\n

\u7b80\u5316 SQL \u8bed\u53e5\u7684\u91cd\u8981\u65b9\u6cd5\u5c31\u662f\u91c7\u7528\u4e34\u65f6\u8868\u6682\u5b58\u4e2d\u95f4\u7ed3\u679c\u3002\u4f46\u662f\u4e34\u65f6\u8868\u7684\u597d\u5904\u8fdc\u8fdc\u4e0d\u6b62\u8fd9\u4e9b\uff0c\u5c06\u4e34\u65f6\u7ed3\u679c\u6682\u5b58\u5728\u4e34\u65f6\u8868\uff0c\u540e\u9762\u7684\u67e5\u8be2\u5c31\u5728 tempdb \u4e2d\u4e86\uff0c\u8fd9\u53ef\u4ee5\u907f\u514d\u7a0b\u5e8f\u4e2d\u591a\u6b21\u626b\u63cf\u4e3b\u8868\uff0c\u4e5f\u5927\u5927\u51cf\u5c11\u4e86\u7a0b\u5e8f\u6267\u884c\u4e2d\u201c\u5171\u4eab\u9501\u201d\u963b\u585e\u201c\u66f4\u65b0\u9501\u201d\uff0c\u51cf\u5c11\u4e86\u963b\u585e\uff0c\u63d0\u9ad8\u4e86\u5e76\u53d1\u6027\u80fd\u3002<\/span><\/p>\n


<\/p>\n

18\u3001\u4e00\u4e9b SQL \u67e5\u8be2\u8bed\u53e5\u5e94\u52a0\u4e0a nolock\uff0c\u8bfb\u3001\u5199\u662f\u4f1a\u76f8\u4e92\u963b\u585e\u7684\uff0c\u4e3a\u4e86\u63d0\u9ad8\u5e76\u53d1\u6027\u80fd\u3002\u5bf9\u4e8e\u4e00\u4e9b\u67e5\u8be2\uff0c\u53ef\u4ee5\u52a0\u4e0a nolock\uff0c\u8fd9\u6837\u8bfb\u7684\u65f6\u5019\u53ef\u4ee5\u5141\u8bb8\u5199\uff0c\u4f46\u7f3a\u70b9\u662f\u53ef\u80fd\u8bfb\u5230\u672a\u63d0\u4ea4\u7684\u810f\u6570\u636e\u3002<\/span><\/p>\n


<\/p>\n

\u4f7f\u7528 nolock \u67093\u6761\u539f\u5219\uff1a<\/span><\/p>\n


<\/p>\n

    \n
  • \n

    \u67e5\u8be2\u7684\u7ed3\u679c\u7528\u4e8e\u201c\u63d2\u3001\u5220\u3001\u6539\u201d\u7684\u4e0d\u80fd\u52a0 nolock\uff1b<\/span><\/p>\n<\/li>\n

  • \n

    \u67e5\u8be2\u7684\u8868\u5c5e\u4e8e\u9891\u7e41\u53d1\u751f\u9875\u5206\u88c2\u7684\uff0c\u614e\u7528 nolock \uff1b<\/span><\/p>\n<\/li>\n

  • \n

    \u4f7f\u7528\u4e34\u65f6\u8868\u4e00\u6837\u53ef\u4ee5\u4fdd\u5b58\u201c\u6570\u636e\u524d\u5f71\u201d\uff0c\u8d77\u5230\u7c7b\u4f3c Oracle \u7684 undo \u8868\u7a7a\u95f4\u7684\u529f\u80fd\uff0c\u80fd\u91c7\u7528\u4e34\u65f6\u8868\u63d0\u9ad8\u5e76\u53d1\u6027\u80fd\u7684\uff0c\u4e0d\u8981\u7528 nolock\u3002<\/span><\/p>\n<\/li>\n<\/ul>\n


    <\/p>\n

    19\u3001\u5e38\u89c1\u7684\u7b80\u5316\u89c4\u5219\u5982\u4e0b\uff1a<\/span><\/p>\n


    <\/p>\n

    \u4e0d\u8981\u6709\u8d85\u8fc7 5 \u4e2a\u4ee5\u4e0a\u7684\u8868\u8fde\u63a5\uff08JOIN\uff09\uff0c\u8003\u8651\u4f7f\u7528\u4e34\u65f6\u8868\u6216\u8868\u53d8\u91cf\u5b58\u653e\u4e2d\u95f4\u7ed3\u679c\u3002\u5c11\u7528\u5b50\u67e5\u8be2\uff0c\u89c6\u56fe\u5d4c\u5957\u4e0d\u8981\u8fc7\u6df1\uff0c\u4e00\u822c\u89c6\u56fe\u5d4c\u5957\u4e0d\u8981\u8d85\u8fc7 2 \u4e2a\u4e3a\u5b9c\u3002<\/span><\/p>\n


    <\/p>\n

    20\u3001\u5c06\u9700\u8981\u67e5\u8be2\u7684\u7ed3\u679c\u9884\u5148\u8ba1\u7b97\u597d\u653e\u5728\u8868\u4e2d\uff0c\u67e5\u8be2\u7684\u65f6\u5019\u518dSelect\u3002\u8fd9\u5728SQL7.0\u4ee5\u524d\u662f\u6700\u91cd\u8981\u7684\u624b\u6bb5\uff0c\u4f8b\u5982\u533b\u9662\u7684\u4f4f\u9662\u8d39\u8ba1\u7b97\u3002<\/span><\/p>\n


    <\/p>\n

    21\u3001\u7528 OR \u7684\u5b57\u53e5\u53ef\u4ee5\u5206\u89e3\u6210\u591a\u4e2a\u67e5\u8be2\uff0c\u5e76\u4e14\u901a\u8fc7 UNION \u8fde\u63a5\u591a\u4e2a\u67e5\u8be2\u3002\u4ed6\u4eec\u7684\u901f\u5ea6\u53ea\u540c\u662f\u5426\u4f7f\u7528\u7d22\u5f15\u6709\u5173\uff0c\u5982\u679c\u67e5\u8be2\u9700\u8981\u7528\u5230\u8054\u5408\u7d22\u5f15\uff0c\u7528 UNION all \u6267\u884c\u7684\u6548\u7387\u66f4\u9ad8\u3002\u591a\u4e2a OR \u7684\u5b57\u53e5\u6ca1\u6709\u7528\u5230\u7d22\u5f15\uff0c\u6539\u5199\u6210 UNION \u7684\u5f62\u5f0f\u518d\u8bd5\u56fe\u4e0e\u7d22\u5f15\u5339\u914d\u3002\u4e00\u4e2a\u5173\u952e\u7684\u95ee\u9898\u662f\u5426\u7528\u5230\u7d22\u5f15\u3002<\/span><\/p>\n


    <\/p>\n

    22\u3001\u5728IN\u540e\u9762\u503c\u7684\u5217\u8868\u4e2d\uff0c\u5c06\u51fa\u73b0\u6700\u9891\u7e41\u7684\u503c\u653e\u5728\u6700\u524d\u9762\uff0c\u51fa\u73b0\u5f97\u6700\u5c11\u7684\u653e\u5728\u6700\u540e\u9762\uff0c\u51cf\u5c11\u5224\u65ad\u7684\u6b21\u6570\u3002<\/span><\/p>\n


    <\/p>\n

    23\u3001\u5c3d\u91cf\u5c06\u6570\u636e\u7684\u5904\u7406\u5de5\u4f5c\u653e\u5728\u670d\u52a1\u5668\u4e0a\uff0c\u51cf\u5c11\u7f51\u7edc\u7684\u5f00\u9500\uff0c\u5982\u4f7f\u7528\u5b58\u50a8\u8fc7\u7a0b\u3002<\/span><\/p>\n


    <\/p>\n

    \u5b58\u50a8\u8fc7\u7a0b\u662f\u7f16\u8bd1\u597d\u3001\u4f18\u5316\u8fc7\u3001\u5e76\u4e14\u88ab\u7ec4\u7ec7\u5230\u4e00\u4e2a\u6267\u884c\u89c4\u5212\u91cc\u3001\u4e14\u5b58\u50a8\u5728\u6570\u636e\u5e93\u4e2d\u7684 SQL \u8bed\u53e5\uff0c\u662f\u63a7\u5236\u6d41\u8bed\u8a00\u7684\u96c6\u5408\uff0c\u901f\u5ea6\u5f53\u7136\u5feb\u3002\u53cd\u590d\u6267\u884c\u7684\u52a8\u6001 SQL\uff0c\u53ef\u4ee5\u4f7f\u7528\u4e34\u65f6\u5b58\u50a8\u8fc7\u7a0b\uff0c\u8be5\u8fc7\u7a0b\uff08\u4e34\u65f6\u8868\uff09\u88ab\u653e\u5728 Tempdb \u4e2d\u3002<\/span><\/p>\n


    <\/p>\n

    24\u3001\u5f53\u670d\u52a1\u5668\u7684\u5185\u5b58\u591f\u591a\u65f6\uff0c\u914d\u5236<\/span>\u7ebf\u7a0b\u6570\u91cf = \u6700\u5927\u8fde\u63a5\u6570+5<\/span><\/strong><\/span>\uff0c\u8fd9\u6837\u80fd\u53d1\u6325\u6700\u5927\u7684\u6548\u7387\uff1b\u5426\u5219\u4f7f\u7528\u914d\u5236\u7ebf\u7a0b\u6570\u91cf< \u6700\u5927\u8fde\u63a5\u6570<\/strong>\uff0c\u542f\u7528 SQL SERVER \u7684\u7ebf\u7a0b\u6c60\u6765\u89e3\u51b3\uff0c\u5982\u679c\u8fd8\u662f\u6570\u91cf = \u6700\u5927\u8fde\u63a5\u6570+5<\/strong>\uff0c\u4e25\u91cd\u7684\u635f\u5bb3\u670d\u52a1\u5668\u7684\u6027\u80fd\u3002<\/span><\/p>\n


    <\/p>\n

    25\u3001\u67e5\u8be2\u7684\u5173\u8054\u540c\u5199\u7684\u987a\u5e8f \uff1a<\/span><\/p>\n


    <\/p>\n

    \n
      \n
    • <\/li>\n
    • <\/li>\n
    • <\/li>\n<\/ul>\n
      select<\/span> a.personMemberID, * from<\/span> chineseresume a,personmember b where<\/span> personMemberID = b.referenceid and<\/span> a.personMemberID = 'JCNPRH39681'<\/span> \uff08A = B, B = '\u53f7\u7801'<\/span>\uff09 <\/span><\/code>select<\/span> a.personMemberID, * from<\/span> chineseresume a,personmember b where<\/span> a.personMemberID = b.referenceid and<\/span> a.personMemberID = 'JCNPRH39681'<\/span> and<\/span> b.referenceid = 'JCNPRH39681'<\/span> \uff08A = B, B = '\u53f7\u7801'<\/span>, A = '\u53f7\u7801'<\/span>\uff09 <\/span><\/code>select<\/span> a.personMemberID, * from<\/span> chineseresume a,personmember b where<\/span> b.referenceid = 'JCNPRH39681'<\/span> and<\/span> a.personMemberID = 'JCNPRH39681'<\/span> \uff08B = '\u53f7\u7801'<\/span>, A = '\u53f7\u7801'<\/span>\uff09<\/span><\/code><\/pre>\n<\/section>\n

      <\/p>\n
      26\u3001\u5c3d\u91cf\u4f7f\u7528 EXISTS \u4ee3\u66ff <\/span>select count(1)<\/span> \u6765\u5224\u65ad\u662f\u5426\u5b58\u5728\u8bb0\u5f55\u3002count \u51fd\u6570\u53ea\u6709\u5728\u7edf\u8ba1\u8868\u4e2d\u6240\u6709\u884c\u6570\u65f6\u4f7f\u7528\uff0c\u800c\u4e14 count(1) \u6bd4 count(*) \u66f4\u6709\u6548\u7387\u3002<\/span><\/p>\n

      <\/p>\n
      27\u3001\u5c3d\u91cf\u4f7f\u7528 \u201c>=\u201d\uff0c\u4e0d\u8981\u4f7f\u7528 \u201c>\u201d\u3002<\/span><\/p>\n

      <\/p>\n
      28\u3001\u7d22\u5f15\u7684\u4f7f\u7528\u89c4\u8303\uff1a<\/span><\/p>\n

      <\/p>\n
        \n
      • \n
        \u7d22\u5f15\u7684\u521b\u5efa\u8981\u4e0e\u5e94\u7528\u7ed3\u5408\u8003\u8651\uff0c\u5efa\u8bae\u5927\u7684 OLTP \u8868\u4e0d\u8981\u8d85\u8fc7 6 \u4e2a\u7d22\u5f15\uff1b<\/span><\/p>\n<\/li>\n
      • \n
        \u5c3d\u53ef\u80fd\u7684\u4f7f\u7528\u7d22\u5f15\u5b57\u6bb5\u4f5c\u4e3a\u67e5\u8be2\u6761\u4ef6\uff0c\u5c24\u5176\u662f\u805a\u7c07\u7d22\u5f15\uff0c\u5fc5\u8981\u65f6\u53ef\u4ee5\u901a\u8fc7 index index_name \u6765\u5f3a\u5236\u6307\u5b9a\u7d22\u5f15\uff1b<\/span><\/p>\n<\/li>\n
      • \n
        \u907f\u514d\u5bf9\u5927\u8868\u67e5\u8be2\u65f6\u8fdb\u884c table scan\uff0c\u5fc5\u8981\u65f6\u8003\u8651\u65b0\u5efa\u7d22\u5f15\uff1b<\/span><\/p>\n<\/li>\n
      • \n
        \u5728\u4f7f\u7528\u7d22\u5f15\u5b57\u6bb5\u4f5c\u4e3a\u6761\u4ef6\u65f6\uff0c\u5982\u679c\u8be5\u7d22\u5f15\u662f\u8054\u5408\u7d22\u5f15\uff0c\u90a3\u4e48\u5fc5\u987b\u4f7f\u7528\u5230\u8be5\u7d22\u5f15\u4e2d\u7684\u7b2c\u4e00\u4e2a\u5b57\u6bb5\u4f5c\u4e3a\u6761\u4ef6\u65f6\u624d\u80fd\u4fdd\u8bc1\u7cfb\u7edf\u4f7f\u7528\u8be5\u7d22\u5f15\uff0c\u5426\u5219\u8be5\u7d22\u5f15\u5c06\u4e0d\u4f1a\u88ab\u4f7f\u7528\uff1b<\/span><\/p>\n<\/li>\n
      • \n
        \u8981\u6ce8\u610f\u7d22\u5f15\u7684\u7ef4\u62a4\uff0c\u5468\u671f\u6027\u91cd\u5efa\u7d22\u5f15\uff0c\u91cd\u65b0\u7f16\u8bd1\u5b58\u50a8\u8fc7\u7a0b\u3002\u3000\u3000<\/span><\/p>\n<\/li>\n<\/ul>\n

        <\/p>\n
        29\u3001\u4e0b\u5217 SQL \u6761\u4ef6\u8bed\u53e5\u4e2d\u7684\u5217\u90fd\u5efa\u6709\u6070\u5f53\u7684\u7d22\u5f15\uff0c\u4f46\u6267\u884c\u901f\u5ea6\u5374\u975e\u5e38\u6162\uff1a
        <\/span><\/p>\n

        <\/p>\n
        \n
          \n
        • <\/li>\n
        • <\/li>\n
        • <\/li>\n<\/ul>\n
          SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> substrINg<\/span>(card_no, 1<\/span>, 4<\/span>) = '5378'<\/span> --13\u79d2 <\/span><\/span><\/code>SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> amount\/30<\/span> < 1000<\/span> --11\u79d2 <\/span><\/span><\/code>SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> convert<\/span>(char<\/span>(10<\/span>), date<\/span>, 112<\/span>) = '19991201'<\/span> --10\u79d2<\/span><\/span><\/code><\/pre>\n<\/section>\n

          <\/span><\/p>\n
          \u5206\u6790\uff1a <\/span><\/p>\n

          <\/p>\n
          WHERE \u5b50\u53e5\u4e2d\u5bf9\u5217\u7684\u4efb\u4f55\u64cd\u4f5c\u7ed3\u679c\u90fd\u662f\u5728 SQL \u8fd0\u884c\u65f6\u9010\u5217\u8ba1\u7b97\u5f97\u5230\u7684\uff0c\u56e0\u6b64\u5b83\u4e0d\u5f97\u4e0d\u8fdb\u884c\u8868\u641c\u7d22\uff0c\u800c\u6ca1\u6709\u4f7f\u7528\u8be5\u5217\u4e0a\u9762\u7684\u7d22\u5f15\u3002<\/span><\/p>\n

          <\/p>\n
          \u5982\u679c\u8fd9\u4e9b\u7ed3\u679c\u5728\u67e5\u8be2\u7f16\u8bd1\u65f6\u5c31\u80fd\u5f97\u5230\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u88ab SQL \u4f18\u5316\u5668\u4f18\u5316\uff0c\u4f7f\u7528\u7d22\u5f15\uff0c\u907f\u514d\u8868\u641c\u7d22\uff0c\u56e0\u6b64\u5c06 SQL \u91cd\u5199\u6210\u4e0b\u9762\u8fd9\u6837\uff1a<\/span><\/p>\n
          \n
            \n
          • <\/li>\n
          • <\/li>\n
          • <\/li>\n<\/ul>\n
            SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> card_no like<\/span> '5378%'<\/span> -- < 1\u79d2 <\/span><\/span><\/code>SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> amount < 1000<\/span>*30<\/span> -- < 1\u79d2 <\/span><\/span><\/code>SELECT<\/span> * FROM<\/span> record<\/span> WHERE<\/span> date<\/span> = '1999\/12\/01'<\/span> -- < 1\u79d2<\/span><\/span><\/code><\/pre>\n<\/section>\n

            <\/p>\n
            30\u3001\u5f53\u6709\u4e00\u6279\u5904\u7406\u7684\u63d2\u5165\u6216\u66f4\u65b0\u65f6\uff0c\u7528\u6279\u91cf\u63d2\u5165\u6216\u6279\u91cf\u66f4\u65b0\uff0c\u7edd\u4e0d\u4f1a\u4e00\u6761\u6761\u8bb0\u5f55\u7684\u53bb\u66f4\u65b0\u3002<\/span><\/p>\n

            <\/p>\n
            31\u3001\u5728\u6240\u6709\u7684\u5b58\u50a8\u8fc7\u7a0b\u4e2d\uff0c\u80fd\u591f\u7528 SQL \u8bed\u53e5\u7684\uff0c\u6211\u7edd\u4e0d\u4f1a\u7528\u5faa\u73af\u53bb\u5b9e\u73b0\u3002
            <\/span><\/p>\n

            <\/span><\/p>\n
            \u4f8b\u5982\uff1a\u5217\u51fa\u4e0a\u4e2a\u6708\u7684\u6bcf\u4e00\u5929\uff0c\u6211\u4f1a\u7528 connect by \u53bb\u9012\u5f52\u67e5\u8be2\u4e00\u4e0b\uff0c\u7edd\u4e0d\u4f1a\u53bb\u7528\u5faa\u73af\u4ece\u4e0a\u4e2a\u6708\u7b2c\u4e00\u5929\u5230\u6700\u540e\u4e00\u5929\u3002<\/span>
            <\/p>\n

            <\/p>\n
            32\u3001\u9009\u62e9\u6700\u6709\u6548\u7387\u7684\u8868\u540d\u987a\u5e8f\uff08\u53ea\u5728\u57fa\u4e8e\u89c4\u5219\u7684\u4f18\u5316\u5668\u4e2d\u6709\u6548\uff09\uff1a <\/span><\/p>\n

            <\/p>\n
            Oracle \u7684\u89e3\u6790\u5668\u6309\u7167\u4ece\u53f3\u5230\u5de6\u7684\u987a\u5e8f\u5904\u7406 FROM \u5b50\u53e5\u4e2d\u7684\u8868\u540d\uff0cFROM \u5b50\u53e5\u4e2d\u5199\u5728\u6700\u540e\u7684\u8868\uff08\u57fa\u7840\u8868 driving table\uff09\u5c06\u88ab\u6700\u5148\u5904\u7406\uff0c\u5728 FROM \u5b50\u53e5\u4e2d\u5305\u542b\u591a\u4e2a\u8868\u7684\u60c5\u51b5\u4e0b\uff0c\u4f60\u5fc5\u987b\u9009\u62e9\u8bb0\u5f55\u6761\u6570\u6700\u5c11\u7684\u8868\u4f5c\u4e3a\u57fa\u7840\u8868\u3002<\/span><\/p>\n

            <\/p>\n
            \u5982\u679c\u6709 3 \u4e2a\u4ee5\u4e0a\u7684\u8868\u8fde\u63a5\u67e5\u8be2\uff0c\u90a3\u5c31\u9700\u8981\u9009\u62e9\u4ea4\u53c9\u8868\uff08intersection table\uff09\u4f5c\u4e3a\u57fa\u7840\u8868\uff0c\u4ea4\u53c9\u8868\u662f\u6307\u90a3\u4e2a\u88ab\u5176\u4ed6\u8868\u6240\u5f15\u7528\u7684\u8868\u3002<\/span><\/p>\n

            <\/p>\n
            33\u3001\u63d0\u9ad8 GROUP BY \u8bed\u53e5\u7684\u6548\u7387\uff0c\u53ef\u4ee5\u901a\u8fc7\u5c06\u4e0d\u9700\u8981\u7684\u8bb0\u5f55\u5728 GROUP BY \u4e4b\u524d\u8fc7\u6ee4\u6389\u3002\u4e0b\u9762\u4e24\u4e2a\u67e5\u8be2\u8fd4\u56de\u76f8\u540c\u7ed3\u679c\uff0c\u4f46\u7b2c\u4e8c\u4e2a\u660e\u663e\u5c31\u5feb\u4e86\u8bb8\u591a\u3002 <\/span><\/p>\n

            <\/p>\n
            \u4f4e\u6548\uff1a<\/span><\/p>\n
            \n
              \n
            • <\/li>\n
            • <\/li>\n
            • <\/li>\n
            • <\/li>\n
            • <\/li>\n<\/ul>\n
              SELECT<\/span> JOB, AVG<\/span>(SAL) <\/span><\/code>FROM<\/span> EMP <\/span><\/code>GROUP<\/span> BY<\/span> JOB <\/span><\/code>HAVING<\/span> JOB = 'PRESIDENT'<\/span> <\/span><\/code>OR<\/span> JOB = 'MANAGER'<\/span> <\/span><\/code><\/pre>\n<\/section>\n
              <\/span><\/p>\n
              \u9ad8\u6548\uff1a<\/span><\/p>\n
              \n
                \n
              • <\/li>\n
              • <\/li>\n
              • <\/li>\n
              • <\/li>\n
              • <\/li>\n<\/ul>\n
                SELECT<\/span> JOB, AVG<\/span>(SAL) <\/span><\/code>FROM<\/span> EMP<\/span><\/code>WHERE<\/span> JOB = 'PRESIDENT'<\/span> <\/span><\/code>OR<\/span> JOB = 'MANAGER'<\/span> <\/span><\/code>GROUP<\/span> BY<\/span> JOB<\/span><\/code><\/pre>\n<\/section>\n

                <\/p>\n

                <\/p>\n
                34\u3001SQL \u8bed\u53e5\u7528\u5927\u5199\uff0c\u56e0\u4e3a Oracle \u603b\u662f\u5148\u89e3\u6790 SQL \u8bed\u53e5\uff0c\u628a\u5c0f\u5199\u7684\u5b57\u6bcd\u8f6c\u6362\u6210\u5927\u5199\u7684\u518d\u6267\u884c\u3002<\/span><\/p>\n

                <\/p>\n
                35\u3001\u522b\u540d\u7684\u4f7f\u7528\uff0c\u522b\u540d\u662f\u5927\u578b\u6570\u636e\u5e93\u7684\u5e94\u7528\u6280\u5de7\uff0c\u5c31\u662f\u8868\u540d\u3001\u5217\u540d\u5728\u67e5\u8be2\u4e2d\u4ee5\u4e00\u4e2a\u5b57\u6bcd\u4e3a\u522b\u540d\uff0c\u67e5\u8be2\u901f\u5ea6\u8981\u6bd4\u5efa\u8fde\u63a5\u8868\u5feb 1.5 \u500d\u3002<\/span><\/p>\n

                <\/p>\n
                36\u3001\u907f\u514d\u6b7b\u9501\uff0c\u5728\u4f60\u7684\u5b58\u50a8\u8fc7\u7a0b\u548c\u89e6\u53d1\u5668\u4e2d\u8bbf\u95ee\u540c\u4e00\u4e2a\u8868\u65f6\u603b\u662f\u4ee5\u76f8\u540c\u7684\u987a\u5e8f\uff1b\u4e8b\u52a1\u5e94\u7ecf\u53ef\u80fd\u5730\u7f29\u77ed\uff0c\u5728\u4e00\u4e2a\u4e8b\u52a1\u4e2d\u5e94\u5c3d\u53ef\u80fd\u51cf\u5c11\u6d89\u53ca\u5230\u7684\u6570\u636e\u91cf\uff1b\u6c38\u8fdc\u4e0d\u8981\u5728\u4e8b\u52a1\u4e2d\u7b49\u5f85\u7528\u6237\u8f93\u5165\u3002<\/span><\/p>\n

                <\/p>\n
                37\u3001\u907f\u514d\u4f7f\u7528\u4e34\u65f6\u8868\uff0c\u9664\u975e\u5374\u6709\u9700\u8981\uff0c\u5426\u5219\u5e94\u5c3d\u91cf\u907f\u514d\u4f7f\u7528\u4e34\u65f6\u8868\uff0c\u76f8\u53cd\uff0c\u53ef\u4ee5\u4f7f\u7528\u8868\u53d8\u91cf\u4ee3\u66ff\u3002\u5927\u591a\u6570\u65f6\u5019\uff0899%\uff09\uff0c\u8868\u53d8\u91cf\u9a7b\u624e\u5728\u5185\u5b58\u4e2d\uff0c\u56e0\u6b64\u901f\u5ea6\u6bd4\u4e34\u65f6\u8868\u66f4\u5feb\uff0c\u4e34\u65f6\u8868\u9a7b\u624e\u5728 TempDb \u6570\u636e\u5e93\u4e2d\uff0c\u56e0\u6b64\u4e34\u65f6\u8868\u4e0a\u7684\u64cd\u4f5c\u9700\u8981\u8de8\u6570\u636e\u5e93\u901a\u4fe1\uff0c\u901f\u5ea6\u81ea\u7136\u6162\u3002<\/span><\/p>\n

                <\/p>\n
                38\u3001\u6700\u597d\u4e0d\u8981\u4f7f\u7528\u89e6\u53d1\u5668\uff1a<\/span><\/p>\n

                <\/p>\n
                  \n
                • \n
                  \u89e6\u53d1\u4e00\u4e2a\u89e6\u53d1\u5668\uff0c\u6267\u884c\u4e00\u4e2a\u89e6\u53d1\u5668\u4e8b\u4ef6\u672c\u8eab\u5c31\u662f\u4e00\u4e2a\u8017\u8d39\u8d44\u6e90\u7684\u8fc7\u7a0b\uff1b<\/span><\/p>\n<\/li>\n
                • \n
                  \u5982\u679c\u80fd\u591f\u4f7f\u7528\u7ea6\u675f\u5b9e\u73b0\u7684\uff0c\u5c3d\u91cf\u4e0d\u8981\u4f7f\u7528\u89e6\u53d1\u5668\uff1b<\/span><\/p>\n<\/li>\n
                • \n
                  \u4e0d\u8981\u4e3a\u4e0d\u540c\u7684\u89e6\u53d1\u4e8b\u4ef6\uff08Insert\u3001Update \u548c Delete\uff09\u4f7f\u7528\u76f8\u540c\u7684\u89e6\u53d1\u5668\uff1b<\/span><\/p>\n<\/li>\n
                • \n
                  \u4e0d\u8981\u5728\u89e6\u53d1\u5668\u4e2d\u4f7f\u7528\u4e8b\u52a1\u578b\u4ee3\u7801\u3002<\/span><\/p>\n<\/li>\n<\/ul>\n

                  <\/p>\n
                  39\u3001\u7d22\u5f15\u521b\u5efa\u89c4\u5219\uff1a <\/span><\/p>\n

                  <\/p>\n
                    \n
                  • \n
                    \u8868\u7684\u4e3b\u952e\u3001\u5916\u952e\u5fc5\u987b\u6709\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u6570\u636e\u91cf\u8d85\u8fc7 300 \u7684\u8868\u5e94\u8be5\u6709\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u7ecf\u5e38\u4e0e\u5176\u4ed6\u8868\u8fdb\u884c\u8fde\u63a5\u7684\u8868\uff0c\u5728\u8fde\u63a5\u5b57\u6bb5\u4e0a\u5e94\u8be5\u5efa\u7acb\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u7ecf\u5e38\u51fa\u73b0\u5728 WHERE \u5b50\u53e5\u4e2d\u7684\u5b57\u6bb5\uff0c\u7279\u522b\u662f\u5927\u8868\u7684\u5b57\u6bb5\uff0c\u5e94\u8be5\u5efa\u7acb\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u7d22\u5f15\u5e94\u8be5\u5efa\u5728\u9009\u62e9\u6027\u9ad8\u7684\u5b57\u6bb5\u4e0a\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u7d22\u5f15\u5e94\u8be5\u5efa\u5728\u5c0f\u5b57\u6bb5\u4e0a\uff0c\u5bf9\u4e8e\u5927\u7684\u6587\u672c\u5b57\u6bb5\u751a\u81f3\u8d85\u957f\u5b57\u6bb5\uff0c\u4e0d\u8981\u5efa\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u590d\u5408\u7d22\u5f15\u7684\u5efa\u7acb\u9700\u8981\u8fdb\u884c\u4ed4\u7ec6\u5206\u6790\uff0c\u5c3d\u91cf\u8003\u8651\u7528\u5355\u5b57\u6bb5\u7d22\u5f15\u4ee3\u66ff\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u6b63\u786e\u9009\u62e9\u590d\u5408\u7d22\u5f15\u4e2d\u7684\u4e3b\u5217\u5b57\u6bb5\uff0c\u4e00\u822c\u662f\u9009\u62e9\u6027\u8f83\u597d\u7684\u5b57\u6bb5\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u590d\u5408\u7d22\u5f15\u7684\u51e0\u4e2a\u5b57\u6bb5\u662f\u5426\u7ecf\u5e38\u540c\u65f6\u4ee5 AND \u65b9\u5f0f\u51fa\u73b0\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\uff1f\u5355\u5b57\u6bb5\u67e5\u8be2\u662f\u5426\u6781\u5c11\u751a\u81f3\u6ca1\u6709\uff1f\u5982\u679c\u662f\uff0c\u5219\u53ef\u4ee5\u5efa\u7acb\u590d\u5408\u7d22\u5f15\uff1b\u5426\u5219\u8003\u8651\u5355\u5b57\u6bb5\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u5982\u679c\u590d\u5408\u7d22\u5f15\u4e2d\u5305\u542b\u7684\u5b57\u6bb5\u7ecf\u5e38\u5355\u72ec\u51fa\u73b0\u5728 WHERE <\/span>\u5b50\u53e5\u4e2d\uff0c\u5219\u5206\u89e3\u4e3a\u591a\u4e2a\u5355\u5b57\u6bb5\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u5982\u679c\u590d\u5408\u7d22\u5f15\u6240\u5305\u542b\u7684\u5b57\u6bb5\u8d85\u8fc7 3 \u4e2a\uff0c\u90a3\u4e48\u4ed4\u7ec6\u8003\u8651\u5176\u5fc5\u8981\u6027\uff0c\u8003\u8651\u51cf\u5c11\u590d\u5408\u7684\u5b57\u6bb5\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u5982\u679c\u65e2\u6709\u5355\u5b57\u6bb5\u7d22\u5f15\uff0c\u53c8\u6709\u8fd9\u51e0\u4e2a\u5b57\u6bb5\u4e0a\u7684\u590d\u5408\u7d22\u5f15\uff0c\u4e00\u822c\u53ef\u4ee5\u5220\u9664\u590d\u5408\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u9891\u7e41\u8fdb\u884c\u6570\u636e\u64cd\u4f5c\u7684\u8868\uff0c\u4e0d\u8981\u5efa\u7acb\u592a\u591a\u7684\u7d22\u5f15\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u5220\u9664\u65e0\u7528\u7684\u7d22\u5f15\uff0c\u907f\u514d\u5bf9\u6267\u884c\u8ba1\u5212\u9020\u6210\u8d1f\u9762\u5f71\u54cd\uff1b <\/span><\/p>\n<\/li>\n
                  • \n
                    \u8868\u4e0a\u5efa\u7acb\u7684\u6bcf\u4e2a\u7d22\u5f15\u90fd\u4f1a\u589e\u52a0\u5b58\u50a8\u5f00\u9500\uff0c\u7d22\u5f15\u5bf9\u4e8e\u63d2\u5165\u3001\u5220\u9664\u3001\u66f4\u65b0\u64cd\u4f5c\u4e5f\u4f1a\u589e\u52a0\u5904\u7406\u4e0a\u7684\u5f00\u9500\u3002\u53e6\u5916\uff0c\u8fc7\u591a\u7684\u590d\u5408\u7d22\u5f15\uff0c\u5728\u6709\u5355\u5b57\u6bb5\u7d22\u5f15\u7684\u60c5\u51b5\u4e0b\uff0c\u4e00\u822c\u90fd\u662f\u6ca1\u6709\u5b58\u5728\u4ef7\u503c\u7684\uff1b\u76f8\u53cd\uff0c\u8fd8\u4f1a\u964d\u4f4e\u6570\u636e\u589e\u52a0\u5220\u9664\u65f6\u7684\u6027\u80fd\uff0c\u7279\u522b\u662f\u5bf9\u9891\u7e41\u66f4\u65b0\u7684\u8868\u6765\u8bf4\uff0c\u8d1f\u9762\u5f71\u54cd\u66f4\u5927\u3002 <\/span><\/p>\n<\/li>\n
                  • \n
                    \u5c3d\u91cf\u4e0d\u8981\u5bf9\u6570\u636e\u5e93\u4e2d\u67d0\u4e2a\u542b\u6709\u5927\u91cf\u91cd\u590d\u7684\u503c\u7684\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\u3002<\/span><\/p>\n<\/li>\n<\/ul>\n

                    <\/p>\n
                    40\u3001MySQL \u67e5\u8be2\u4f18\u5316\u603b\u7ed3\uff1a<\/span><\/p>\n

                    <\/p>\n
                    \u4f7f\u7528\u6162\u67e5\u8be2\u65e5\u5fd7\u53bb\u53d1\u73b0\u6162\u67e5\u8be2\uff0c\u4f7f\u7528\u6267\u884c\u8ba1\u5212\u53bb\u5224\u65ad\u67e5\u8be2\u662f\u5426\u6b63\u5e38\u8fd0\u884c\uff0c\u603b\u662f\u53bb\u6d4b\u8bd5\u4f60\u7684\u67e5\u8be2\u770b\u770b\u662f\u5426\u4ed6\u4eec\u8fd0\u884c\u5728\u6700\u4f73\u72b6\u6001\u4e0b\u3002<\/span><\/p>\n

                    <\/p>\n
                    \u4e45\u800c\u4e45\u4e4b\u6027\u80fd\u603b\u4f1a\u53d8\u5316\uff0c\u907f\u514d\u5728\u6574\u4e2a\u8868\u4e0a\u4f7f\u7528 count(*)\uff0c\u5b83\u53ef\u80fd\u9501\u4f4f\u6574\u5f20\u8868\uff0c\u4f7f\u67e5\u8be2\u4fdd\u6301\u4e00\u81f4\u4ee5\u4fbf\u540e\u7eed\u76f8\u4f3c\u7684\u67e5\u8be2\u53ef\u4ee5\u4f7f\u7528\u67e5\u8be2\u7f13\u5b58\uff0c\u5728\u9002\u5f53\u7684\u60c5\u5f62\u4e0b\u4f7f\u7528 GROUP BY \u800c\u4e0d\u662f DISTINCT\uff0c\u5728 WHERE\u3001GROUP BY \u548c ORDER BY \u5b50\u53e5\u4e2d\u4f7f\u7528\u6709\u7d22\u5f15\u7684\u5217\uff0c\u4fdd\u6301\u7d22\u5f15\u7b80\u5355\uff0c\u4e0d\u5728\u591a\u4e2a\u7d22\u5f15\u4e2d\u5305\u542b\u540c\u4e00\u4e2a\u5217\u3002<\/span><\/p>\n

                    <\/p>\n
                    \u6709\u65f6\u5019 MySQL \u4f1a\u4f7f\u7528\u9519\u8bef\u7684\u7d22\u5f15\uff0c\u5bf9\u4e8e\u8fd9\u79cd\u60c5\u51b5\u4f7f\u7528 USE INDEX\uff0c\u68c0\u67e5\u4f7f\u7528 SQL_MODE=STRICT \u7684\u95ee\u9898\uff0c\u5bf9\u4e8e\u8bb0\u5f55\u6570\u5c0f\u4e8e5\u7684\u7d22\u5f15\u5b57\u6bb5\uff0c\u5728 UNION \u7684\u65f6\u5019\u4f7f\u7528LIMIT\u4e0d\u662f\u662f\u7528OR\u3002 <\/span><\/p>\n

                    <\/p>\n
                    \u4e3a\u4e86\u907f\u514d\u5728\u66f4\u65b0\u524d SELECT\uff0c\u4f7f\u7528 INSERT ON DUPLICATE KEY \u6216\u8005 INSERT IGNORE\uff1b\u4e0d\u8981\u7528 UPDATE \u53bb\u5b9e\u73b0\uff0c\u4e0d\u8981\u4f7f\u7528 MAX\uff1b\u4f7f\u7528\u7d22\u5f15\u5b57\u6bb5\u548c ORDER BY\u5b50\u53e5 LIMIT M\uff0cN \u5b9e\u9645\u4e0a\u53ef\u4ee5\u51cf\u7f13\u67e5\u8be2\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u6709\u8282\u5236\u5730\u4f7f\u7528\uff0c\u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528 UNION \u4ee3\u66ff\u5b50\u67e5\u8be2\uff0c\u5728\u91cd\u65b0\u542f\u52a8\u7684 MySQL\uff0c\u8bb0\u5f97\u6765\u6e29\u6696\u4f60\u7684\u6570\u636e\u5e93\uff0c\u4ee5\u786e\u4fdd\u6570\u636e\u5728\u5185\u5b58\u548c\u67e5\u8be2\u901f\u5ea6\u5feb\uff0c\u8003\u8651\u6301\u4e45\u8fde\u63a5\uff0c\u800c\u4e0d\u662f\u591a\u4e2a\u8fde\u63a5\uff0c\u4ee5\u51cf\u5c11\u5f00\u9500\u3002<\/span><\/p>\n

                    <\/p>\n
                    \u57fa\u51c6\u67e5\u8be2\uff0c\u5305\u62ec\u4f7f\u7528\u670d\u52a1\u5668\u4e0a\u7684\u8d1f\u8f7d\uff0c\u6709\u65f6\u4e00\u4e2a\u7b80\u5355\u7684\u67e5\u8be2\u53ef\u4ee5\u5f71\u54cd\u5176\u4ed6\u67e5\u8be2\uff0c\u5f53\u8d1f\u8f7d\u589e\u52a0\u5728\u670d\u52a1\u5668\u4e0a\uff0c\u4f7f\u7528 SHOW PROCESSLIST \u67e5\u770b\u6162\u7684\u548c\u6709\u95ee\u9898\u7684\u67e5\u8be2\uff0c\u5728\u5f00\u53d1\u73af\u5883\u4e2d\u4ea7\u751f\u7684\u955c\u50cf\u6570\u636e\u4e2d\u6d4b\u8bd5\u7684\u6240\u6709\u53ef\u7591\u7684\u67e5\u8be2\u3002<\/span><\/p>\n

                    <\/p>\n
                    41\u3001MySQL \u5907\u4efd\u8fc7\u7a0b\uff1a<\/span><\/p>\n

                    <\/p>\n
                      \n
                    • \n
                      \u4ece\u4e8c\u7ea7\u590d\u5236\u670d\u52a1\u5668\u4e0a\u8fdb\u884c\u5907\u4efd\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5728\u8fdb\u884c\u5907\u4efd\u671f\u95f4\u505c\u6b62\u590d\u5236\uff0c\u4ee5\u907f\u514d\u5728\u6570\u636e\u4f9d\u8d56\u548c\u5916\u952e\u7ea6\u675f\u4e0a\u51fa\u73b0\u4e0d\u4e00\u81f4\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5f7b\u5e95\u505c\u6b62 MySQL\uff0c\u4ece\u6570\u636e\u5e93\u6587\u4ef6\u8fdb\u884c\u5907\u4efd\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5982\u679c\u4f7f\u7528 MySQL dump \u8fdb\u884c\u5907\u4efd\uff0c\u8bf7\u540c\u65f6\u5907\u4efd\u4e8c\u8fdb\u5236\u65e5\u5fd7\u6587\u4ef6 \u2013 \u786e\u4fdd\u590d\u5236\u6ca1\u6709\u4e2d\u65ad\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u4e0d\u8981\u4fe1\u4efb LVM \u5feb\u7167\uff0c\u8fd9\u5f88\u53ef\u80fd\u4ea7\u751f\u6570\u636e\u4e0d\u4e00\u81f4\uff0c\u5c06\u6765\u4f1a\u7ed9\u4f60\u5e26\u6765\u9ebb\u70e6\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u4e3a\u4e86\u66f4\u5bb9\u6613\u8fdb\u884c\u5355\u8868\u6062\u590d\uff0c\u4ee5\u8868\u4e3a\u5355\u4f4d\u5bfc\u51fa\u6570\u636e\u2014\u2014\u5982\u679c\u6570\u636e\u662f\u4e0e\u5176\u4ed6\u8868\u9694\u79bb\u7684\u3002 <\/span><\/p>\n<\/li>\n
                    • \n
                      \u5f53\u4f7f\u7528 mysqldump \u65f6\u8bf7\u4f7f\u7528 \u2013opt\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5728\u5907\u4efd\u4e4b\u524d\u68c0\u67e5\u548c\u4f18\u5316\u8868\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u4e3a\u4e86\u66f4\u5feb\u7684\u8fdb\u884c\u5bfc\u5165\uff0c\u5728\u5bfc\u5165\u65f6\u4e34\u65f6\u7981\u7528\u5916\u952e\u7ea6\u675f\u3002\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u4e3a\u4e86\u66f4\u5feb\u7684\u8fdb\u884c\u5bfc\u5165\uff0c\u5728\u5bfc\u5165\u65f6\u4e34\u65f6\u7981\u7528\u552f\u4e00\u6027\u68c0\u6d4b\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5728\u6bcf\u4e00\u6b21\u5907\u4efd\u540e\u8ba1\u7b97\u6570\u636e\u5e93\uff0c\u8868\u4ee5\u53ca\u7d22\u5f15\u7684\u5c3a\u5bf8\uff0c\u4ee5\u4fbf\u66f4\u591f\u76d1\u63a7\u6570\u636e\u5c3a\u5bf8\u7684\u589e\u957f\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u901a\u8fc7\u81ea\u52a8\u8c03\u5ea6\u811a\u672c\u76d1\u63a7\u590d\u5236\u5b9e\u4f8b\u7684\u9519\u8bef\u548c\u5ef6\u8fdf\uff1b<\/span><\/p>\n<\/li>\n
                    • \n
                      \u5b9a\u671f\u6267\u884c\u5907\u4efd\u3002<\/span><\/p>\n<\/li>\n<\/ul>\n

                      <\/p>\n
                      42\u3001\u67e5\u8be2\u7f13\u51b2\u5e76\u4e0d\u81ea\u52a8\u5904\u7406\u7a7a\u683c\uff0c\u56e0\u6b64\uff0c\u5728\u5199 SQL \u8bed\u53e5\u65f6\uff0c\u5e94\u5c3d\u91cf\u51cf\u5c11\u7a7a\u683c\u7684\u4f7f\u7528\uff0c\u5c24\u5176\u662f\u5728 SQL \u9996\u548c\u5c3e\u7684\u7a7a\u683c\uff08\u56e0\u4e3a\u67e5\u8be2\u7f13\u51b2\u5e76\u4e0d\u81ea\u52a8\u622a\u53d6\u9996\u5c3e\u7a7a\u683c\uff09\u3002<\/span><\/p>\n

                      <\/p>\n
                      43\u3001member \u7528 mid \u505a\u6807\u51c6\u8fdb\u884c\u5206\u8868\u65b9\u4fbf\u67e5\u8be2\u4e48\uff1f\u4e00\u822c\u7684\u4e1a\u52a1\u9700\u6c42\u4e2d\u57fa\u672c\u4e0a\u90fd\u662f\u4ee5 username \u4e3a\u67e5\u8be2\u4f9d\u636e\uff0c\u6b63\u5e38\u5e94\u5f53\u662f username \u505a hash \u53d6\u6a21\u6765\u5206\u8868\u3002<\/span><\/p>\n

                      <\/p>\n
                      \u800c\u5206\u8868\u7684\u8bdd MySQL \u7684 partition \u529f\u80fd\u5c31\u662f\u5e72\u8fd9\u4e2a\u7684\uff0c\u5bf9\u4ee3\u7801\u662f\u900f\u660e\u7684\uff1b<\/span>\u5728\u4ee3\u7801\u5c42\u9762\u53bb\u5b9e\u73b0\u8c8c\u4f3c\u662f\u4e0d\u5408\u7406\u7684\u3002<\/span><\/p>\n

                      <\/p>\n
                      44\u3001\u6211\u4eec\u5e94\u8be5\u4e3a\u6570\u636e\u5e93\u91cc\u7684\u6bcf\u5f20\u8868\u90fd\u8bbe\u7f6e\u4e00\u4e2a ID \u505a\u4e3a\u5176\u4e3b\u952e\uff0c\u800c\u4e14\u6700\u597d\u7684\u662f\u4e00\u4e2a INT \u578b\u7684\uff08\u63a8\u8350\u4f7f\u7528 UNSIGNED\uff09\uff0c\u5e76\u8bbe\u7f6e\u4e0a\u81ea\u52a8\u589e\u52a0\u7684 AUTO_INCREMENT \u6807\u5fd7\u3002<\/span><\/p>\n

                      <\/p>\n
                      45\u3001\u5728\u6240\u6709\u7684\u5b58\u50a8\u8fc7\u7a0b\u548c\u89e6\u53d1\u5668\u7684\u5f00\u59cb\u5904\u8bbe\u7f6e SET NOCOUNT ON\uff0c\u5728\u7ed3\u675f\u65f6\u8bbe\u7f6e SET NOCOUNT OFF\u3002<\/span>\u65e0\u9700\u5728\u6267\u884c\u5b58\u50a8\u8fc7\u7a0b\u548c\u89e6\u53d1\u5668\u7684\u6bcf\u4e2a\u8bed\u53e5\u540e\u5411\u5ba2\u6237\u7aef\u53d1\u9001 DONE_IN_PROC \u6d88\u606f\u3002<\/span><\/p>\n

                      <\/p>\n
                      46\u3001MySQL \u67e5\u8be2\u53ef\u4ee5\u542f\u7528\u9ad8\u901f\u67e5\u8be2\u7f13\u5b58\u3002\u8fd9\u662f\u63d0\u9ad8\u6570\u636e\u5e93\u6027\u80fd\u7684\u6709\u6548MySQL\u4f18\u5316\u65b9\u6cd5\u4e4b\u4e00\u3002\u5f53\u540c\u4e00\u4e2a\u67e5\u8be2\u88ab\u6267\u884c\u591a\u6b21\u65f6\uff0c\u4ece\u7f13\u5b58\u4e2d\u63d0\u53d6\u6570\u636e\u548c\u76f4\u63a5\u4ece\u6570\u636e\u5e93\u4e2d\u8fd4\u56de\u6570\u636e\u5feb\u5f88\u591a\u3002<\/span><\/p>\n

                      <\/p>\n
                      47\u3001EXPLAIN SELECT \u67e5\u8be2\u7528\u6765\u8ddf\u8e2a\u67e5\u770b\u6548\u679c\uff1a<\/span><\/p>\n

                      <\/p>\n
                      \u4f7f\u7528 EXPLAIN \u5173\u952e\u5b57\u53ef\u4ee5\u8ba9\u4f60\u77e5\u9053 MySQL \u662f\u5982\u4f55\u5904\u7406\u4f60\u7684 SQL \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<\/span>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\u3002<\/span><\/p>\n

                      <\/p>\n
                      48\u3001\u5f53\u53ea\u8981\u4e00\u884c\u6570\u636e\u65f6\u4f7f\u7528 LIMIT 1 \uff1a<\/span><\/p>\n

                      <\/p>\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<\/span><\/p>\n

                      <\/p>\n
                      \u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u52a0\u4e0a LIMIT 1 \u53ef\u4ee5\u589e\u52a0\u6027\u80fd\u3002<\/span>\u8fd9\u6837\u4e00\u6765\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<\/span><\/p>\n

                      <\/p>\n
                      49\u3001\u9009\u62e9\u8868\u5408\u9002\u5b58\u50a8\u5f15\u64ce\uff1a <\/span><\/p>\n

                      <\/p>\n
                        \n
                      • \n
                        myisam\uff1a<\/span><\/strong>\u5e94\u7528\u65f6\u4ee5\u8bfb\u548c\u63d2\u5165\u64cd\u4f5c\u4e3a\u4e3b\uff0c\u53ea\u6709\u5c11\u91cf\u7684\u66f4\u65b0\u548c\u5220\u9664\uff0c\u5e76\u4e14\u5bf9\u4e8b\u52a1\u7684\u5b8c\u6574\u6027\uff0c\u5e76\u53d1\u6027\u8981\u6c42\u4e0d\u662f\u5f88\u9ad8\u7684\u3002 <\/span><\/p>\n<\/li>\n
                      • \n
                        InnoDB\uff1a<\/span><\/strong>\u4e8b\u52a1\u5904\u7406\uff0c\u4ee5\u53ca\u5e76\u53d1\u6761\u4ef6\u4e0b\u8981\u6c42\u6570\u636e\u7684\u4e00\u81f4\u6027\u3002\u9664\u4e86\u63d2\u5165\u548c\u67e5\u8be2\u5916\uff0c\u5305\u62ec\u5f88\u591a\u7684\u66f4\u65b0\u548c\u5220\u9664\u3002\uff08InnoDB \u6709\u6548\u5730\u964d\u4f4e\u5220\u9664\u548c\u66f4\u65b0\u5bfc\u81f4\u7684\u9501\u5b9a\uff09\u3002<\/span><\/p>\n
                        \u5bf9\u4e8e\u652f\u6301\u4e8b\u52a1\u7684 InnoDB\u7c7b \u578b\u7684\u8868\u6765\u8bf4\uff0c\u5f71\u54cd\u901f\u5ea6\u7684\u4e3b\u8981\u539f\u56e0\u662f AUTOCOMMIT \u9ed8\u8ba4\u8bbe\u7f6e\u662f\u6253\u5f00\u7684\uff0c\u800c\u4e14\u7a0b\u5e8f\u6ca1\u6709\u663e\u5f0f\u8c03\u7528 BEGIN \u5f00\u59cb\u4e8b\u52a1\uff0c\u5bfc\u81f4\u6bcf\u63d2\u5165\u4e00\u6761\u90fd\u81ea\u52a8\u63d0\u4ea4\uff0c\u4e25\u91cd\u5f71\u54cd\u4e86\u901f\u5ea6\u3002\u53ef\u4ee5\u5728\u6267\u884c SQL \u524d\u8c03\u7528 begin\uff0c\u591a\u6761 SQL \u5f62\u6210\u4e00\u4e2a\u4e8b\u7269\uff08\u5373\u4f7f autocommit \u6253\u5f00\u4e5f\u53ef\u4ee5\uff09\uff0c\u5c06\u5927\u5927\u63d0\u9ad8\u6027\u80fd\u3002<\/span><\/p>\n<\/li>\n<\/ul>\n

                        <\/p>\n
                        50\u3001\u4f18\u5316\u8868\u7684\u6570\u636e\u7c7b\u578b\uff0c\u9009\u62e9\u5408\u9002\u7684\u6570\u636e\u7c7b\u578b\uff1a <\/span><\/p>\n

                        <\/p>\n
                        \u539f\u5219\uff1a<\/span><\/strong>\u66f4\u5c0f\u901a\u5e38\u66f4\u597d\uff0c\u7b80\u5355\u5c31\u597d\uff0c\u6240\u6709\u5b57\u6bb5\u90fd\u5f97\u6709\u9ed8\u8ba4\u503c\uff0c\u5c3d\u91cf\u907f\u514d NULL\u3002 <\/span><\/p>\n

                        <\/p>\n
                        \u4f8b\u5982\uff1a\u6570\u636e\u5e93\u8868\u8bbe\u8ba1\u65f6\u5019\u66f4\u5c0f\u7684\u5360\u78c1\u76d8\u7a7a\u95f4\u5c3d\u53ef\u80fd\u4f7f\u7528\u66f4\u5c0f\u7684\u6574\u6570\u7c7b\u578b\u3002(mediumint \u5c31\u6bd4 int \u66f4\u5408\u9002) <\/span><\/p>\n

                        <\/p>\n
                        \u6bd4\u5982\u65f6\u95f4\u5b57\u6bb5\uff1adatetime \u548c timestamp\u3002datetime \u5360\u75288\u4e2a\u5b57\u8282\uff0ctimestamp \u5360\u75284\u4e2a\u5b57\u8282\uff0c\u53ea\u7528\u4e86\u4e00\u534a\u3002\u800c timestamp \u8868\u793a\u7684\u8303\u56f4\u662f 1970\u20142037 \u9002\u5408\u505a\u66f4\u65b0\u65f6\u95f4\u3002<\/span><\/p>\n

                        <\/p>\n
                        MySQL\u53ef\u4ee5\u5f88\u597d\u7684\u652f\u6301\u5927\u6570\u636e\u91cf\u7684\u5b58\u53d6\uff0c\u4f46\u662f\u4e00\u822c\u8bf4\u6765\uff0c\u6570\u636e\u5e93\u4e2d\u7684\u8868\u8d8a\u5c0f\uff0c\u5728\u5b83\u4e0a\u9762\u6267\u884c\u7684\u67e5\u8be2\u4e5f\u5c31\u4f1a\u8d8a\u5feb\u3002 <\/span><\/p>\n

                        <\/p>\n
                        \u56e0\u6b64\uff0c\u5728\u521b\u5efa\u8868\u7684\u65f6\u5019\uff0c\u4e3a\u4e86\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u8868\u4e2d\u5b57\u6bb5\u7684\u5bbd\u5ea6\u8bbe\u5f97\u5c3d\u53ef\u80fd\u5c0f\u3002<\/span><\/p>\n

                        <\/p>\n
                        \u4f8b\u5982\uff1a<\/span>\u5728\u5b9a\u4e49\u90ae\u653f\u7f16\u7801\u8fd9\u4e2a\u5b57\u6bb5\u65f6\uff0c\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u4e3a CHAR(255)\uff0c\u663e\u7136\u7ed9\u6570\u636e\u5e93\u589e\u52a0\u4e86\u4e0d\u5fc5\u8981\u7684\u7a7a\u95f4\u3002<\/span>\u751a\u81f3\u4f7f\u7528VARCHAR \u8fd9\u79cd\u7c7b\u578b\u4e5f\u662f\u591a\u4f59\u7684\uff0c\u56e0\u4e3a CHAR(6) \u5c31\u53ef\u4ee5\u5f88\u597d\u7684\u5b8c\u6210\u4efb\u52a1\u4e86\u3002<\/span><\/p>\n

                        <\/p>\n
                        \u540c\u6837\u7684\uff0c\u5982\u679c\u53ef\u4ee5\u7684\u8bdd\uff0c\u6211\u4eec\u5e94\u8be5\u4f7f\u7528 MEDIUMINT \u800c\u4e0d\u662f BIGIN \u6765\u5b9a\u4e49\u6574\u578b\u5b57\u6bb5\uff0c\u5e94\u8be5\u5c3d\u91cf\u628a\u5b57\u6bb5\u8bbe\u7f6e\u4e3a NOT NULL\uff0c\u8fd9\u6837\u5728\u5c06\u6765\u6267\u884c\u67e5\u8be2\u7684\u65f6\u5019\uff0c\u6570\u636e\u5e93\u4e0d\u7528\u53bb\u6bd4\u8f83 NULL \u503c\u3002 <\/span><\/p>\n

                        <\/p>\n
                        \u5bf9\u4e8e\u67d0\u4e9b\u6587\u672c\u5b57\u6bb5\uff0c\u4f8b\u5982\u201c\u7701\u4efd\u201d\u6216\u8005\u201c\u6027\u522b\u201d\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u5b83\u4eec\u5b9a\u4e49\u4e3a ENUM \u7c7b\u578b\u3002\u56e0\u4e3a\u5728 MySQL \u4e2d\uff0cENUM \u7c7b\u578b\u88ab\u5f53\u4f5c\u6570\u503c\u578b\u6570\u636e\u6765\u5904\u7406\uff0c<\/span>\u800c\u6570\u503c\u578b\u6570\u636e\u88ab\u5904\u7406\u8d77\u6765\u7684\u901f\u5ea6\u8981\u6bd4\u6587\u672c\u7c7b\u578b\u5feb\u5f97\u591a\u3002\u8fd9\u6837\uff0c\u6211\u4eec\u53c8\u53ef\u4ee5\u63d0\u9ad8\u6570\u636e\u5e93\u7684\u6027\u80fd\u3002<\/span><\/p>\n

                        <\/p>\n
                        51\u3001\u5b57\u7b26\u4e32\u6570\u636e\u7c7b\u578b\uff1achar, varchar, text \u9009\u62e9\u533a\u522b\u3002<\/span><\/p>\n

                        <\/p>\n
                        52\u3001\u4efb\u4f55\u5bf9\u5217\u7684\u64cd\u4f5c\u90fd\u5c06\u5bfc\u81f4\u8868\u626b\u63cf\uff0c\u5b83\u5305\u62ec\u6570\u636e\u5e93\u51fd\u6570\u3001\u8ba1\u7b97\u8868\u8fbe\u5f0f\u7b49\u7b49\uff0c\u67e5\u8be2\u65f6\u8981\u5c3d\u53ef\u80fd\u5c06\u64cd\u4f5c\u79fb\u81f3\u7b49\u53f7\u53f3\u8fb9\u3002<\/span><\/p>\n

                        <\/span><\/p>\n
                        \u901a\u8fc7\u7f51\u4e0a\u641c\u7d22\u6574\u7406\u51fa\u6765\uff0c\u591a\u8c22\u67e5\u770b<\/span><\/p>\n

                        <\/span><\/p>\n
                        <\/mp-common-profile><\/section>\n

                        <\/p>\n
                        <\/mp-style-type><\/p>\n
                        \n
                        \u672c\u7bc7\u6587\u7ae0\u6765\u6e90\u4e8e\u5fae\u4fe1\u516c\u4f17\u53f7:                 \u6280\u672f\u8001\u7537\u5b69              <\/p>\n<\/blockquote>\n<\/div>\n","raw":"","protected":false},"excerpt":{"rendered":"
                        \u672c\u6587\u4f1a\u63d0\u5230 52 \u6761 SQL \u8bed\u53e5\u6027\u80fd\u4f18\u5316\u7b56\u7565\u3002 1\u3001\u5bf9\u67e5\u8be2\u8fdb\u884c\u4f18\u5316\uff0c\u5e94\u5c3d\u91cf\u907f\u514d\u5168\u8868\u626b\u63cf\uff0c\u9996\u5148\u5e94\u8003\u8651\u5728 WHERE \u53ca ORDER …<\/p>\n","protected":false},"author":1,"featured_media":2239,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[3],"tags":[],"class_list":["post-2240","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-mysql"],"post_thumbnail_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526-150x150.jpeg","content_first_image":null,"post_medium_image_300":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526-300x128.jpeg","post_thumbnail_image_624":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526.jpeg","post_frist_image":null,"post_medium_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526-300x128.jpeg","post_large_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526.jpeg","post_full_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/06\/20230627150506526.jpeg","post_all_images":[],"videoAdId":"","listAd":"0","listAdId":"","listAdEvery":6,"total_comments":0,"category_name":"MySQL","post_date":"2023-06-27","like_count":"0","praiseWord":"\u9f13\u52b1","copyright_state":"","excitationAd":"0","rewardedVideoAdId":"","detailAdId":"","detailAd":"0","enterpriseMinapp":"0","audios":[],"postImageUrl":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230519082947553.jpg","avatarurls":[],"related_posts":null,"pageviews":322,"next_post_id":2348,"next_post_title":"\u804a\u804a Sharding-JDBC \u5206\u5e93\u5206\u8868\uff08\u4e00\uff09","previous_post_id":2062,"previous_post_title":"SQL\u9ad8\u7ea7\u7bc7\uff5e\u89c6\u56fe\u548c\u4e34\u65f6\u8868","_links":{"self":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/2240","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/comments?post=2240"}],"version-history":[{"count":0,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/2240\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media\/2239"}],"wp:attachment":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media?parent=2240"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/categories?post=2240"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/tags?post=2240"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}