\u6211\u4eec\u8981\u505a\u5230\u4e0d\u4f46\u4f1a\u5199SQL\uff0c\u8fd8\u8981\u505a\u5230\u5199\u51fa\u6027\u80fd\u4f18\u826f\u7684SQL\u8bed\u53e5\u3002<\/p>\n
\uff081\uff09\u9009\u62e9\u6700\u6709\u6548\u7387\u7684\u8868\u540d\u987a\u5e8f(\u53ea\u5728\u57fa\u4e8e\u89c4\u5219\u7684\u4f18\u5316\u5668\u4e2d\u6709\u6548)\uff1a<\/p>\n
oracle\u7684\u89e3\u6790\u5668\u6309\u7167\u4ece\u53f3\u5230\u5de6\u7684\u987a\u5e8f\u5904\u7406FROM\u5b50\u53e5\u4e2d\u7684\u8868\u540d\uff0cFROM\u5b50\u53e5\u4e2d\u5199\u5728\u6700\u540e\u7684\u8868(\u57fa\u7840\u8868 driving table)\u5c06\u88ab\u6700\u5148\u5904\u7406\uff0c\u5728FROM\u5b50\u53e5\u4e2d\u5305\u542b\u591a\u4e2a\u8868\u7684\u60c5\u51b5\u4e0b,\u4f60\u5fc5\u987b\u9009\u62e9\u8bb0\u5f55\u6761\u6570\u6700\u5c11\u7684\u8868\u4f5c\u4e3a\u57fa\u7840\u8868\u3002\u5982\u679c\u67093\u4e2a\u4ee5\u4e0a\u7684\u8868\u8fde\u63a5\u67e5\u8be2, \u90a3\u5c31\u9700\u8981\u9009\u62e9\u4ea4\u53c9\u8868(intersection table)\u4f5c\u4e3a\u57fa\u7840\u8868, \u4ea4\u53c9\u8868\u662f\u6307\u90a3\u4e2a\u88ab\u5176\u4ed6\u8868\u6240\u5f15\u7528\u7684\u8868\u3002<\/p>\n
\uff082\uff09Where\u5b50\u53e5\u4e2d\u7684\u8fde\u63a5\u987a\u5e8f\uff1a<\/p>\n
oracle\u91c7\u7528\u81ea\u4e0b\u800c\u4e0a\u7684\u987a\u5e8f\u89e3\u6790Where\u5b50\u53e5,\u6839\u636e\u8fd9\u4e2a\u539f\u7406,\u8868\u4e4b\u95f4\u7684\u8fde\u63a5\u5fc5\u987b\u5199\u5728\u5176\u4ed6Where\u6761\u4ef6\u4e4b\u524d, \u90a3\u4e9b\u53ef\u4ee5\u8fc7\u6ee4\u6389\u6700\u5927\u6570\u91cf\u8bb0\u5f55\u7684\u6761\u4ef6\u5fc5\u987b\u5199\u5728Where\u5b50\u53e5\u7684\u672b\u5c3e\u3002<\/p>\n
\uff083\uff09Select\u5b50\u53e5\u4e2d\u907f\u514d\u4f7f\u7528\u2018*\u2019\uff1a<\/p>\n
oracle\u5728\u89e3\u6790\u7684\u8fc7\u7a0b\u4e2d, \u4f1a\u5c06\u2018*\u2019\u4f9d\u6b21\u8f6c\u6362\u6210\u6240\u6709\u7684\u5217\u540d, \u8fd9\u4e2a\u5de5\u4f5c\u662f\u901a\u8fc7\u67e5\u8be2\u6570\u636e\u5b57\u5178\u5b8c\u6210\u7684, \u8fd9\u610f\u5473\u7740\u5c06\u8017\u8d39\u66f4\u591a\u7684\u65f6\u95f4\u3002<\/p>\n
\uff084\uff09\u51cf\u5c11\u8bbf\u95ee\u6570\u636e\u5e93\u7684\u6b21\u6570\uff1a<\/p>\n
oracle\u5728\u5185\u90e8\u6267\u884c\u4e86\u8bb8\u591a\u5de5\u4f5c: \u89e3\u6790SQL\u8bed\u53e5, \u4f30\u7b97\u7d22\u5f15\u7684\u5229\u7528\u7387, \u7ed1\u5b9a\u53d8\u91cf , \u8bfb\u6570\u636e\u5757\u7b49\u3002<\/p>\n
\uff085\uff09\u5728SQL*Plus , SQL*Forms\u548cPro*C\u4e2d\u91cd\u65b0\u8bbe\u7f6eARRAYSIZE\u53c2\u6570, \u53ef\u4ee5\u589e\u52a0\u6bcf\u6b21\u6570\u636e\u5e93\u8bbf\u95ee\u7684\u68c0\u7d22\u6570\u636e\u91cf ,\u5efa\u8bae\u503c\u4e3a200\u3002<\/p>\n
\uff086\uff09\u4f7f\u7528DECODE\u51fd\u6570\u6765\u51cf\u5c11\u5904\u7406\u65f6\u95f4\uff1a<\/p>\n
\u4f7f\u7528DECODE\u51fd\u6570\u53ef\u4ee5\u907f\u514d\u91cd\u590d\u626b\u63cf\u76f8\u540c\u8bb0\u5f55\u6216\u91cd\u590d\u8fde\u63a5\u76f8\u540c\u7684\u8868\u3002<\/p>\n
\uff087\uff09\u6574\u5408\u7b80\u5355,\u65e0\u5173\u8054\u7684\u6570\u636e\u5e93\u8bbf\u95ee\uff1a<\/p>\n
\u5982\u679c\u4f60\u6709\u51e0\u4e2a\u7b80\u5355\u7684\u6570\u636e\u5e93\u67e5\u8be2\u8bed\u53e5,\u4f60\u53ef\u4ee5\u628a\u5b83\u4eec\u6574\u5408\u5230\u4e00\u4e2a\u67e5\u8be2\u4e2d(\u5373\u4f7f\u5b83\u4eec\u4e4b\u95f4\u6ca1\u6709\u5173\u7cfb)\u3002<\/p>\n
\uff088\uff09\u5220\u9664\u91cd\u590d\u8bb0\u5f55\uff1a<\/p>\n
\u6700\u9ad8\u6548\u7684\u5220\u9664\u91cd\u590d\u8bb0\u5f55\u65b9\u6cd5 ( \u56e0\u4e3a\u4f7f\u7528\u4e86ROWID)\u4f8b\u5b50\uff1a<\/p>\n
Delete FROM EMP E Where E.ROWID > (Select MIN(X.ROWID) FROM EMP X Where X.EMP_NO = E.EMP_NO);<\/p>\n
\uff089\uff09\u7528TRUNCATE\u66ff\u4ee3Delete\uff1a<\/p>\n
\u5f53\u5220\u9664\u8868\u4e2d\u7684\u8bb0\u5f55\u65f6,\u5728\u901a\u5e38\u60c5\u51b5\u4e0b, \u56de\u6eda\u6bb5(rollback segments ) \u7528\u6765\u5b58\u653e\u53ef\u4ee5\u88ab\u6062\u590d\u7684\u4fe1\u606f. \u5982\u679c\u4f60\u6ca1\u6709COMMIT\u4e8b\u52a1,ORACLE\u4f1a\u5c06\u6570\u636e\u6062\u590d\u5230\u5220\u9664\u4e4b\u524d\u7684\u72b6\u6001(\u51c6\u786e\u5730\u8bf4\u662f\u6062\u590d\u5230\u6267\u884c\u5220\u9664\u547d\u4ee4\u4e4b\u524d\u7684\u72b6\u51b5) \u800c\u5f53\u8fd0\u7528TRUNCATE\u65f6, \u56de\u6eda\u6bb5\u4e0d\u518d\u5b58\u653e\u4efb\u4f55\u53ef\u88ab\u6062\u590d\u7684\u4fe1\u606f\u3002\u5f53\u547d\u4ee4\u8fd0\u884c\u540e,\u6570\u636e\u4e0d\u80fd\u88ab\u6062\u590d.\u56e0\u6b64\u5f88\u5c11\u7684\u8d44\u6e90\u88ab\u8c03\u7528,\u6267\u884c\u65f6\u95f4\u4e5f\u4f1a\u5f88\u77ed\u3002\uff08TRUNCATE\u53ea\u5728\u5220\u9664\u5168\u8868\u9002\u7528,TRUNCATE\u662fDDL\u4e0d\u662fDML\uff09\u3002<\/p>\n
\uff0810\uff09\u5c3d\u91cf\u591a\u4f7f\u7528COMMIT\uff1a<\/p>\n
\u53ea\u8981\u6709\u53ef\u80fd\uff0c\u5728\u7a0b\u5e8f\u4e2d\u5c3d\u91cf\u591a\u4f7f\u7528COMMIT, \u8fd9\u6837\u7a0b\u5e8f\u7684\u6027\u80fd\u5f97\u5230\u63d0\u9ad8,\u9700\u6c42\u4e5f\u4f1a\u56e0\u4e3aCOMMIT\u6240\u91ca\u653e\u7684\u8d44\u6e90\u800c\u51cf\u5c11\uff0cCOMMIT\u6240\u91ca\u653e\u7684\u8d44\u6e90:<\/p>\n
a. \u56de\u6eda\u6bb5\u4e0a\u7528\u4e8e\u6062\u590d\u6570\u636e\u7684\u4fe1\u606f\u3002<\/p>\n
b. \u88ab\u7a0b\u5e8f\u8bed\u53e5\u83b7\u5f97\u7684\u9501\u3002<\/p>\n
c. redo log buffer \u4e2d\u7684\u7a7a\u95f4\u3002<\/p>\n
d. oracle\u4e3a\u7ba1\u7406\u4e0a\u8ff03\u79cd\u8d44\u6e90\u4e2d\u7684\u5185\u90e8\u82b1\u8d39\u3002<\/p>\n
\uff0811\uff09\u7528Where\u5b50\u53e5\u66ff\u6362HAVING\u5b50\u53e5\uff1a<\/p>\n
\u907f\u514d\u4f7f\u7528HAVING\u5b50\u53e5\uff0cHAVING \u53ea\u4f1a\u5728\u68c0\u7d22\u51fa\u6240\u6709\u8bb0\u5f55\u4e4b\u540e\u624d\u5bf9\u7ed3\u679c\u96c6\u8fdb\u884c\u8fc7\u6ee4\u3002\u8fd9\u4e2a\u5904\u7406\u9700\u8981\u6392\u5e8f,\u603b\u8ba1\u7b49\u64cd\u4f5c\u3002\u5982\u679c\u80fd\u901a\u8fc7Where\u5b50\u53e5\u9650\u5236\u8bb0\u5f55\u7684\u6570\u76ee\uff0c\u90a3\u5c31\u80fd\u51cf\u5c11\u8fd9\u65b9\u9762\u7684\u5f00\u9500\u3002(\u975eoracle\u4e2d)on\u3001where\u3001having\u8fd9\u4e09\u4e2a\u90fd\u53ef\u4ee5\u52a0\u6761\u4ef6\u7684\u5b50\u53e5\u4e2d\uff0con\u662f\u6700\u5148\u6267\u884c\uff0cwhere\u6b21\u4e4b\uff0chaving\u6700\u540e\uff0c\u56e0\u4e3aon\u662f\u5148\u628a\u4e0d\u7b26\u5408\u6761\u4ef6\u7684\u8bb0\u5f55\u8fc7\u6ee4\u540e\u624d\u8fdb\u884c\u7edf\u8ba1\uff0c\u5b83\u5c31\u53ef\u4ee5\u51cf\u5c11\u4e2d\u95f4\u8fd0\u7b97\u8981\u5904\u7406\u7684\u6570\u636e\uff0c\u6309\u7406\u8bf4\u5e94\u8be5\u901f\u5ea6\u662f\u6700\u5feb\u7684\uff0cwhere\u4e5f\u5e94\u8be5\u6bd4having\u5feb\u70b9\u7684\uff0c\u56e0\u4e3a\u5b83\u8fc7\u6ee4\u6570\u636e\u540e\u624d\u8fdb\u884csum\uff0c\u5728\u4e24\u4e2a\u8868\u8054\u63a5\u65f6\u624d\u7528on\u7684\uff0c\u6240\u4ee5\u5728\u4e00\u4e2a\u8868\u7684\u65f6\u5019\uff0c\u5c31\u5269\u4e0bwhere\u8ddfhaving\u6bd4\u8f83\u4e86\u3002\u5728\u8fd9\u5355\u8868\u67e5\u8be2\u7edf\u8ba1\u7684\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u8981\u8fc7\u6ee4\u7684\u6761\u4ef6\u6ca1\u6709\u6d89\u53ca\u5230\u8981\u8ba1\u7b97\u5b57\u6bb5\uff0c\u90a3\u5b83\u4eec\u7684\u7ed3\u679c\u662f\u4e00\u6837\u7684\uff0c\u53ea\u662fwhere\u53ef\u4ee5\u4f7f\u7528rushmore\u6280\u672f\uff0c\u800chaving\u5c31\u4e0d\u80fd\uff0c\u5728\u901f\u5ea6\u4e0a\u540e\u8005\u8981\u6162\u5982\u679c\u8981\u6d89\u53ca\u5230\u8ba1\u7b97\u7684\u5b57\u6bb5\uff0c\u5c31\u8868\u793a\u5728\u6ca1\u8ba1\u7b97\u4e4b\u524d\uff0c\u8fd9\u4e2a\u5b57\u6bb5\u7684\u503c\u662f\u4e0d\u786e\u5b9a\u7684\uff0c\u6839\u636e\u4e0a\u7bc7\u5199\u7684\u5de5\u4f5c\u6d41\u7a0b\uff0cwhere\u7684\u4f5c\u7528\u65f6\u95f4\u662f\u5728\u8ba1\u7b97\u4e4b\u524d\u5c31\u5b8c\u6210\u7684\uff0c\u800chaving\u5c31\u662f\u5728\u8ba1\u7b97\u540e\u624d\u8d77\u4f5c\u7528\u7684\uff0c\u6240\u4ee5\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e24\u8005\u7684\u7ed3\u679c\u4f1a\u4e0d\u540c\u3002\u5728\u591a\u8868\u8054\u63a5\u67e5\u8be2\u65f6\uff0con\u6bd4where\u66f4\u65e9\u8d77\u4f5c\u7528\u3002\u7cfb\u7edf\u9996\u5148\u6839\u636e\u5404\u4e2a\u8868\u4e4b\u95f4\u7684\u8054\u63a5\u6761\u4ef6\uff0c\u628a\u591a\u4e2a\u8868\u5408\u6210\u4e00\u4e2a\u4e34\u65f6\u8868\u540e\uff0c\u518d\u7531where\u8fdb\u884c\u8fc7\u6ee4\uff0c\u7136\u540e\u518d\u8ba1\u7b97\uff0c\u8ba1\u7b97\u5b8c\u540e\u518d\u7531having\u8fdb\u884c\u8fc7\u6ee4\u3002\u7531\u6b64\u53ef\u89c1\uff0c\u8981\u60f3\u8fc7\u6ee4\u6761\u4ef6\u8d77\u5230\u6b63\u786e\u7684\u4f5c\u7528\uff0c\u9996\u5148\u8981\u660e\u767d\u8fd9\u4e2a\u6761\u4ef6\u5e94\u8be5\u5728\u4ec0\u4e48\u65f6\u5019\u8d77\u4f5c\u7528\uff0c\u7136\u540e\u518d\u51b3\u5b9a\u653e\u5728\u90a3\u91cc\u3002<\/p>\n
\uff0812\uff09\u51cf\u5c11\u5bf9\u8868\u7684\u67e5\u8be2\uff1a<\/p>\n
\u5728\u542b\u6709\u5b50\u67e5\u8be2\u7684SQL\u8bed\u53e5\u4e2d,\u8981\u7279\u522b\u6ce8\u610f\u51cf\u5c11\u5bf9\u8868\u7684\u67e5\u8be2\u3002\u4f8b\u5b50\uff1a<\/p>\n
Select TAB_NAME FROM TABLES Where (TAB_NAME,DB_VER) = ( SelectTAB_NAME,DB_VER FROM TAB_COLUMNS Where VERSION = 604)<\/p>\n
\uff0813\uff09\u901a\u8fc7\u5185\u90e8\u51fd\u6570\u63d0\u9ad8SQL\u6548\u7387\uff1a<\/p>\n
\u590d\u6742\u7684SQL\u5f80\u5f80\u727a\u7272\u4e86\u6267\u884c\u6548\u7387\u3002\u80fd\u591f\u638c\u63e1\u4e0a\u9762\u7684\u8fd0\u7528\u51fd\u6570\u89e3\u51b3\u95ee\u9898\u7684\u65b9\u6cd5\u5728\u5b9e\u9645\u5de5\u4f5c\u4e2d\u662f\u975e\u5e38\u6709\u610f\u4e49\u7684\u3002<\/p>\n
\uff0814\uff09\u4f7f\u7528\u8868\u7684\u522b\u540d(Alias)\uff1a<\/p>\n
\u5f53\u5728SQL\u8bed\u53e5\u4e2d\u8fde\u63a5\u591a\u4e2a\u8868\u65f6, \u8bf7\u4f7f\u7528\u8868\u7684\u522b\u540d\u5e76\u628a\u522b\u540d\u524d\u7f00\u4e8e\u6bcf\u4e2aColumn\u4e0a\u3002\u8fd9\u6837\u4e00\u6765,\u5c31\u53ef\u4ee5\u51cf\u5c11\u89e3\u6790\u7684\u65f6\u95f4\u5e76\u51cf\u5c11\u90a3\u4e9b\u7531Column\u6b67\u4e49\u5f15\u8d77\u7684\u8bed\u6cd5\u9519\u8bef\u3002<\/p>\n
\uff0815\uff09\u7528EXISTS\u66ff\u4ee3IN\u3001\u7528NOT EXISTS\u66ff\u4ee3NOT IN\uff1a<\/p>\n
\u5728\u8bb8\u591a\u57fa\u4e8e\u57fa\u7840\u8868\u7684\u67e5\u8be2\u4e2d\uff0c\u4e3a\u4e86\u6ee1\u8db3\u4e00\u4e2a\u6761\u4ef6,\u5f80\u5f80\u9700\u8981\u5bf9\u53e6\u4e00\u4e2a\u8868\u8fdb\u884c\u8054\u63a5\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4f7f\u7528EXISTS(\u6216NOT EXISTS)\u901a\u5e38\u5c06\u63d0\u9ad8\u67e5\u8be2\u7684\u6548\u7387\u3002\u5728\u5b50\u67e5\u8be2\u4e2d\uff0cNOT IN\u5b50\u53e5\u5c06\u6267\u884c\u4e00\u4e2a\u5185\u90e8\u7684\u6392\u5e8f\u548c\u5408\u5e76\u3002\u65e0\u8bba\u5728\u54ea\u79cd\u60c5\u51b5\u4e0b\uff0cNOT IN\u90fd\u662f\u6700\u4f4e\u6548\u7684 (\u56e0\u4e3a\u5b83\u5bf9\u5b50\u67e5\u8be2\u4e2d\u7684\u8868\u6267\u884c\u4e86\u4e00\u4e2a\u5168\u8868\u904d\u5386)\u3002\u4e3a\u4e86\u907f\u514d\u4f7f\u7528NOT IN \uff0c\u6211\u4eec\u53ef\u4ee5\u628a\u5b83\u6539\u5199\u6210\u5916\u8fde\u63a5(Outer Joins)\u6216NOT EXISTS\u3002<\/p>\n
\u4f8b\u5b50\uff1a<\/p>\n
\uff08\u9ad8\u6548\uff09Select * FROM EMP (\u57fa\u7840\u8868) Where EMPNO > 0 AND EXISTS (Select \u2018X’ FROM DEPT Where DEPT.DEPTNO = EMP.DEPTNO AND LOC = \u2018MELB’)(\u4f4e\u6548)Select * FROM EMP (\u57fa\u7840\u8868) Where EMPNO > 0 AND DEPTNO IN(Select DEPTNO FROM DEPT Where LOC = \u2018MELB’)<\/p>\n
\uff0816\uff09\u8bc6\u522b\u2018\u4f4e\u6548\u6267\u884c\u2019\u7684SQL\u8bed\u53e5\uff1a<\/p>\n
\u867d\u7136\u76ee\u524d\u5404\u79cd\u5173\u4e8eSQL\u4f18\u5316\u7684\u56fe\u5f62\u5316\u5de5\u5177\u5c42\u51fa\u4e0d\u7a77,\u4f46\u662f\u5199\u51fa\u81ea\u5df1\u7684SQL\u5de5\u5177\u6765\u89e3\u51b3\u95ee\u9898\u59cb\u7ec8\u662f\u4e00\u4e2a\u6700\u597d\u7684\u65b9\u6cd5\uff1a<\/p>\n
Select EXECUTIONS , DISK_READS, BUFFER_GETS, ROUND((BUFFER_GETS-DISK_READS)\/BUFFER_GETS,2) Hit_radio, ROUND(DISK_READS\/EXECUTIONS,2) Reads_per_run, SQL_TEXT FROM V$SQLAREA Where EXECUTIONS>0 AND BUFFER_GETS > 0 AND (BUFFER_GETS-DISK_READS)\/BUFFER_GETS < 0.8 orDER BY 4 DESC;<\/p>\n
\u7d22\u5f15\u662f\u8868\u7684\u4e00\u4e2a\u6982\u5ff5\u90e8\u5206\uff0c\u7528\u6765\u63d0\u9ad8\u68c0\u7d22\u6570\u636e\u7684\u6548\u7387\uff0cOracle\u4f7f\u7528\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u81ea\u5e73\u8861B-tree\u7ed3\u6784\u3002\u901a\u5e38,\u901a\u8fc7\u7d22\u5f15\u67e5\u8be2\u6570\u636e\u6bd4\u5168\u8868\u626b\u63cf\u8981\u5feb\u3002\u5f53Oracle\u627e\u51fa\u6267\u884c\u67e5\u8be2\u548cUpdate\u8bed\u53e5\u7684\u6700\u4f73\u8def\u5f84\u65f6, oracle\u4f18\u5316\u5668\u5c06\u4f7f\u7528\u7d22\u5f15\u3002\u540c\u6837\u5728\u8054\u7ed3\u591a\u4e2a\u8868\u65f6\u4f7f\u7528\u7d22\u5f15\u4e5f\u53ef\u4ee5\u63d0\u9ad8\u6548\u7387\u3002\u53e6\u4e00\u4e2a\u4f7f\u7528\u7d22\u5f15\u7684\u597d\u5904\u662f,\u5b83\u63d0\u4f9b\u4e86\u4e3b\u952e(primary key)\u7684\u552f\u4e00\u6027\u9a8c\u8bc1\u3002\u90a3\u4e9bLONG\u6216LONG RAW\u6570\u636e\u7c7b\u578b, \u4f60\u53ef\u4ee5\u7d22\u5f15\u51e0\u4e4e\u6240\u6709\u7684\u5217\u3002\u901a\u5e38, \u5728\u5927\u578b\u8868\u4e2d\u4f7f\u7528\u7d22\u5f15\u7279\u522b\u6709\u6548. \u5f53\u7136,\u4f60\u4e5f\u4f1a\u53d1\u73b0, \u5728\u626b\u63cf\u5c0f\u8868\u65f6\uff0c\u4f7f\u7528\u7d22\u5f15\u540c\u6837\u80fd\u63d0\u9ad8\u6548\u7387\u3002\u867d\u7136\u4f7f\u7528\u7d22\u5f15\u80fd\u5f97\u5230\u67e5\u8be2\u6548\u7387\u7684\u63d0\u9ad8,\u4f46\u662f\u6211\u4eec\u4e5f\u5fc5\u987b\u6ce8\u610f\u5230\u5b83\u7684\u4ee3\u4ef7\u3002\u7d22\u5f15\u9700\u8981\u7a7a\u95f4\u6765\u5b58\u50a8,\u4e5f\u9700\u8981\u5b9a\u671f\u7ef4\u62a4, \u6bcf\u5f53\u6709\u8bb0\u5f55\u5728\u8868\u4e2d\u589e\u51cf\u6216\u7d22\u5f15\u5217\u88ab\u4fee\u6539\u65f6, \u7d22\u5f15\u672c\u8eab\u4e5f\u4f1a\u88ab\u4fee\u6539\u3002\u8fd9\u610f\u5473\u7740\u6bcf\u6761\u8bb0\u5f55\u7684Insert\uff0cDelete \uff0c Update\u5c06\u4e3a\u6b64\u591a\u4ed8\u51fa4\u3001 5\u6b21\u7684\u78c1\u76d8I\/O \u3002\u56e0\u4e3a\u7d22\u5f15\u9700\u8981\u989d\u5916\u7684\u5b58\u50a8\u7a7a\u95f4\u548c\u5904\u7406\uff0c\u90a3\u4e9b\u4e0d\u5fc5\u8981\u7684\u7d22\u5f15\u53cd\u800c\u4f1a\u4f7f\u67e5\u8be2\u53cd\u5e94\u65f6\u95f4\u53d8\u6162\u3002\u5b9a\u671f\u7684\u91cd\u6784\u7d22\u5f15\u662f\u6709\u5fc5\u8981\u7684\uff1a<\/p>\n
Alter INDEX <INDEXNAME> REBUILD <TABLESPACENAME><\/p>\n
\uff0818\uff09\u7528EXISTS\u66ff\u6362DISTINCT\uff1a<\/p>\n
\u5f53\u63d0\u4ea4\u4e00\u4e2a\u5305\u542b\u4e00\u5bf9\u591a\u8868\u4fe1\u606f(\u6bd4\u5982\u90e8\u95e8\u8868\u548c\u96c7\u5458\u8868)\u7684\u67e5\u8be2\u65f6\uff0c\u907f\u514d\u5728Select\u5b50\u53e5\u4e2d\u4f7f\u7528DISTINCT\u3002\u4e00\u822c\u53ef\u4ee5\u8003\u8651\u7528EXIST\u66ff\u6362\uff0c EXISTS \u4f7f\u67e5\u8be2\u66f4\u4e3a\u8fc5\u901f\uff0c\u56e0\u4e3aRDBMS\u6838\u5fc3\u6a21\u5757\u5c06\u5728\u5b50\u67e5\u8be2\u7684\u6761\u4ef6\u4e00\u65e6\u6ee1\u8db3\u540e\uff0c\u7acb\u523b\u8fd4\u56de\u7ed3\u679c\u3002\u4f8b\u5b50\uff1a<\/p>\n
(\u4f4e\u6548): Select DISTINCT DEPT_NO,DEPT_NAME FROM DEPT D , EMP E Where D.DEPT_NO = E.DEPT_NO (\u9ad8\u6548): Select DEPT_NO,DEPT_NAME FROM DEPT D Where EXISTS ( Select \u2018X’ FROM EMP E Where E.DEPT_NO = D.DEPT_NO);<\/p>\n
\uff0819\uff09SQL\u8bed\u53e5\u7528\u5927\u5199\u7684\uff1b\u56e0\u4e3aOracle\u603b\u662f\u5148\u89e3\u6790SQL\u8bed\u53e5\uff0c\u628a\u5c0f\u5199\u7684\u5b57\u6bcd\u8f6c\u6362\u6210\u5927\u5199\u7684\u518d\u6267\u884c\u3002<\/p>\n
\uff0820\uff09\u5728Java\u4ee3\u7801\u4e2d\u5c3d\u91cf\u5c11\u7528\u8fde\u63a5\u7b26\u201c\uff0b\u201d\u8fde\u63a5\u5b57\u7b26\u4e32\u3002<\/p>\n
\uff0821\uff09\u907f\u514d\u5728\u7d22\u5f15\u5217\u4e0a\u4f7f\u7528NOT\u901a\u5e38\uff0c\u6211\u4eec\u8981\u907f\u514d\u5728\u7d22\u5f15\u5217\u4e0a\u4f7f\u7528NOT, NOT\u4f1a\u4ea7\u751f\u5728\u548c\u5728\u7d22\u5f15\u5217\u4e0a\u4f7f\u7528\u51fd\u6570\u76f8\u540c\u7684\u5f71\u54cd\u3002\u5f53Oracle\u201c\u9047\u5230\u201dNOT,\u4ed6\u5c31\u4f1a\u505c\u6b62\u4f7f\u7528\u7d22\u5f15\u8f6c\u800c\u6267\u884c\u5168\u8868\u626b\u63cf\u3002<\/p>\n
\uff0822\uff09\u907f\u514d\u5728\u7d22\u5f15\u5217\u4e0a\u4f7f\u7528\u8ba1\u7b97\u3002Where\u5b50\u53e5\u4e2d\uff0c\u5982\u679c\u7d22\u5f15\u5217\u662f\u51fd\u6570\u7684\u4e00\u90e8\u5206\u3002\u4f18\u5316\u5668\u5c06\u4e0d\u4f7f\u7528\u7d22\u5f15\u800c\u4f7f\u7528\u5168\u8868\u626b\u63cf\u3002<\/p>\n
\u4e3e\u4f8b:<\/p>\n
\u4f4e\u6548\uff1a Select \u2026 FROM DEPT Where SAL * 12 > 25000; \u9ad8\u6548: Select \u2026 FROM DEPT Where SAL > 25000\/12;<\/p>\n
\uff0823\uff09\u7528>=\u66ff\u4ee3>\uff1a<\/p>\n
\u9ad8\u6548\uff1aSelect * FROM EMP Where DEPTNO >=4 \u4f4e\u6548: Select * FROM EMP Where DEPTNO >3<\/p>\n
\u4e24\u8005\u7684\u533a\u522b\u5728\u4e8e\uff0c\u524d\u8005DBMS\u5c06\u76f4\u63a5\u8df3\u5230\u7b2c\u4e00\u4e2aDEPT\u7b49\u4e8e4\u7684\u8bb0\u5f55\u800c\u540e\u8005\u5c06\u9996\u5148\u5b9a\u4f4d\u5230DEPTNO=3\u7684\u8bb0\u5f55\u5e76\u4e14\u5411\u524d\u626b\u63cf\u5230\u7b2c\u4e00\u4e2aDEPT\u5927\u4e8e3\u7684\u8bb0\u5f55\u3002<\/p>\n
\uff0824\uff09\u7528UNION\u66ff\u6362OR (\u9002\u7528\u4e8e\u7d22\u5f15\u5217)\uff1a<\/p>\n
\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u7528UNION\u66ff\u6362Where\u5b50\u53e5\u4e2d\u7684OR\u5c06\u4f1a\u8d77\u5230\u8f83\u597d\u7684\u6548\u679c\u3002\u5bf9\u7d22\u5f15\u5217\u4f7f\u7528OR\u5c06\u9020\u6210\u5168\u8868\u626b\u63cf\u3002\u6ce8\u610f\uff0c\u4ee5\u4e0a\u89c4\u5219\u53ea\u9488\u5bf9\u591a\u4e2a\u7d22\u5f15\u5217\u6709\u6548\u3002\u5982\u679c\u6709column\u6ca1\u6709\u88ab\u7d22\u5f15\uff0c\u67e5\u8be2\u6548\u7387\u53ef\u80fd\u4f1a\u56e0\u4e3a\u4f60\u6ca1\u6709\u9009\u62e9OR\u800c\u964d\u4f4e\u3002\u5728\u4e0b\u9762\u7684\u4f8b\u5b50\u4e2d\uff0cLOC_ID \u548cREGION\u4e0a\u90fd\u5efa\u6709\u7d22\u5f15\u3002<\/p>\n
\u9ad8\u6548\uff1aSelect LOC_ID \u3002 LOC_DESC \uff0cREGION FROM LOCATION Where LOC_ID = 10 UNION Select LOC_ID \uff0cLOC_DESC \uff0cREGION FROM LOCATION Where REGION = \u201cMELBOURNE\u201d<\/p>\n
\u4f4e\u6548: Select LOC_ID \uff0cLOC_DESC \uff0cREGION FROM LOCATION Where LOC_ID = 10 or REGION = \u201cMELBOURNE\u201d<\/p>\n
\uff0825\uff09\u7528IN\u6765\u66ff\u6362OR\uff1a<\/p>\n
\u8fd9\u662f\u4e00\u6761\u7b80\u5355\u6613\u8bb0\u7684\u89c4\u5219\uff0c\u4f46\u662f\u5b9e\u9645\u7684\u6267\u884c\u6548\u679c\u8fd8\u987b\u68c0\u9a8c\uff0c\u5728Oracle8i\u4e0b\uff0c\u4e24\u8005\u7684\u6267\u884c\u8def\u5f84\u4f3c\u4e4e\u662f\u76f8\u540c\u7684:\u3000<\/p>\n
\u4f4e\u6548:<\/p>\n
Select\u2026. FROM LOCATION Where LOC_ID = 10 or LOC_ID = 20 or LOC_ID = 30<\/p>\n
\u9ad8\u6548\uff1a<\/p>\n
Select\u2026 FROM LOCATION Where LOC_IN IN (10,20,30);<\/p>\n
\uff0826\uff09\u907f\u514d\u5728\u7d22\u5f15\u5217\u4e0a\u4f7f\u7528IS NULL\u548cIS NOT NULL\uff1a<\/p>\n
\u907f\u514d\u5728\u7d22\u5f15\u4e2d\u4f7f\u7528\u4efb\u4f55\u53ef\u4ee5\u4e3a\u7a7a\u7684\u5217\uff0cOracle\u5c06\u65e0\u6cd5\u4f7f\u7528\u8be5\u7d22\u5f15\u3002\u5bf9\u4e8e\u5355\u5217\u7d22\u5f15\uff0c\u5982\u679c\u5217\u5305\u542b\u7a7a\u503c\uff0c\u7d22\u5f15\u4e2d\u5c06\u4e0d\u5b58\u5728\u6b64\u8bb0\u5f55\u3002\u5bf9\u4e8e\u590d\u5408\u7d22\u5f15\uff0c\u5982\u679c\u6bcf\u4e2a\u5217\u90fd\u4e3a\u7a7a\uff0c\u7d22\u5f15\u4e2d\u540c\u6837\u4e0d\u5b58\u5728\u6b64\u8bb0\u5f55\u3002\u5982\u679c\u81f3\u5c11\u6709\u4e00\u4e2a\u5217\u4e0d\u4e3a\u7a7a\uff0c\u5219\u8bb0\u5f55\u5b58\u5728\u4e8e\u7d22\u5f15\u4e2d\u3002\u4e3e\u4f8b\uff1a\u5982\u679c\u552f\u4e00\u6027\u7d22\u5f15\u5efa\u7acb\u5728\u8868\u7684A\u5217\u548cB\u5217\u4e0a\uff0c\u5e76\u4e14\u8868\u4e2d\u5b58\u5728\u4e00\u6761\u8bb0\u5f55\u7684A\uff0cB\u503c\u4e3a(123\uff0cnull)\uff0c oracle\u5c06\u4e0d\u63a5\u53d7\u4e0b\u4e00\u6761\u5177\u6709\u76f8\u540cA\uff0cB\u503c\uff08123,null\uff09\u7684\u8bb0\u5f55(\u63d2\u5165)\u3002 \u7136\u800c\u5982\u679c\u6240\u6709\u7684\u7d22\u5f15\u5217\u90fd\u4e3a\u7a7a\uff0cOracle\u5c06\u8ba4\u4e3a\u6574\u4e2a\u952e\u503c\u4e3a\u7a7a\u800c\u7a7a\u4e0d\u7b49\u4e8e\u7a7a\u3002\u56e0\u6b64\u4f60\u53ef\u4ee5\u63d2\u51651000 \u6761\u5177\u6709\u76f8\u540c\u952e\u503c\u7684\u8bb0\u5f55,\u5f53\u7136\u5b83\u4eec\u90fd\u662f\u7a7a! \u56e0\u4e3a\u7a7a\u503c\u4e0d\u5b58\u5728\u4e8e\u7d22\u5f15\u5217\u4e2d,\u6240\u4ee5Where\u5b50\u53e5\u4e2d\u5bf9\u7d22\u5f15\u5217\u8fdb\u884c\u7a7a\u503c\u6bd4\u8f83\u5c06\u4f7fORACLE\u505c\u7528\u8be5\u7d22\u5f15\u3002<\/p>\n
\u4f4e\u6548: (\u7d22\u5f15\u5931\u6548)<\/p>\n
Select \u2026 FROM DEPARTMENT Where DEPT_CODE IS NOT NULL;<\/p>\n
\u9ad8\u6548\uff1a(\u7d22\u5f15\u6709\u6548)<\/p>\n
Select \u2026 FROM DEPARTMENT Where DEPT_CODE >=0;<\/p>\n
\uff0827\uff09\u603b\u662f\u4f7f\u7528\u7d22\u5f15\u7684\u7b2c\u4e00\u4e2a\u5217\uff1a<\/p>\n
\u5982\u679c\u7d22\u5f15\u662f\u5efa\u7acb\u5728\u591a\u4e2a\u5217\u4e0a\uff0c\u53ea\u6709\u5728\u5b83\u7684\u7b2c\u4e00\u4e2a\u5217(leading column)\u88abwhere\u5b50\u53e5\u5f15\u7528\u65f6\uff0c\u4f18\u5316\u5668\u624d\u4f1a\u9009\u62e9\u4f7f\u7528\u8be5\u7d22\u5f15\u3002\u8fd9\u4e5f\u662f\u4e00\u6761\u7b80\u5355\u800c\u91cd\u8981\u7684\u89c4\u5219\uff0c\u5f53\u4ec5\u5f15\u7528\u7d22\u5f15\u7684\u7b2c\u4e8c\u4e2a\u5217\u65f6\uff0c\u4f18\u5316\u5668\u4f7f\u7528\u4e86\u5168\u8868\u626b\u63cf\u800c\u5ffd\u7565\u4e86\u7d22\u5f15\u3002<\/p>\n
\uff0828\uff09\u7528UNION-ALL \u66ff\u6362UNION ( \u5982\u679c\u6709\u53ef\u80fd\u7684\u8bdd)\uff1a<\/p>\n
\u5f53SQL\u8bed\u53e5\u9700\u8981UNION\u4e24\u4e2a\u67e5\u8be2\u7ed3\u679c\u96c6\u5408\u65f6\uff0c\u8fd9\u4e24\u4e2a\u7ed3\u679c\u96c6\u5408\u4f1a\u4ee5UNION-ALL\u7684\u65b9\u5f0f\u88ab\u5408\u5e76\uff0c\u7136\u540e\u5728\u8f93\u51fa\u6700\u7ec8\u7ed3\u679c\u524d\u8fdb\u884c\u6392\u5e8f\u3002\u5982\u679c\u7528UNION ALL\u66ff\u4ee3UNION\uff0c\u8fd9\u6837\u6392\u5e8f\u5c31\u4e0d\u662f\u5fc5\u8981\u4e86\u3002\u6548\u7387\u5c31\u4f1a\u56e0\u6b64\u5f97\u5230\u63d0\u9ad8\u3002\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0cUNION ALL \u5c06\u91cd\u590d\u8f93\u51fa\u4e24\u4e2a\u7ed3\u679c\u96c6\u5408\u4e2d\u76f8\u540c\u8bb0\u5f55\u3002\u56e0\u6b64\u5404\u4f4d\u8fd8\u662f\u8981\u4ece\u4e1a\u52a1\u9700\u6c42\u5206\u6790\u4f7f\u7528UNION ALL\u7684\u53ef\u884c\u6027\u3002 UNION \u5c06\u5bf9\u7ed3\u679c\u96c6\u5408\u6392\u5e8f,\u8fd9\u4e2a\u64cd\u4f5c\u4f1a\u4f7f\u7528\u5230SORT_AREA_SIZE\u8fd9\u5757\u5185\u5b58\u3002\u5bf9\u4e8e\u8fd9\u5757\u5185\u5b58\u7684\u4f18\u5316\u4e5f\u662f\u76f8\u5f53\u91cd\u8981\u7684\u3002\u4e0b\u9762\u7684SQL\u53ef\u4ee5\u7528\u6765\u67e5\u8be2\u6392\u5e8f\u7684\u6d88\u8017\u91cf\uff1a<\/p>\n
\u4f4e\u6548\uff1a Select ACCT_NUM, BALANCE_AMT FROM DEBIT_TRANSACTIONS Where TRAN_DATE = ’31-DEC-95′ UNION Select ACCT_NUM, BALANCE_AMT FROM DEBIT_TRANSACTIONS Where TRAN_DATE = ’31-DEC-95′ \u9ad8\u6548: Select ACCT_NUM, BALANCE_AMT FROM DEBIT_TRANSACTIONS Where TRAN_DATE = ’31-DEC-95′ UNION ALL Select ACCT_NUM, BALANCE_AMT FROM DEBIT_TRANSACTIONS Where TRAN_DATE = ’31-DEC-95′<\/p>\n
\uff0829\uff09\u7528Where\u66ff\u4ee3ORDER BY\uff1a<\/p>\n
orDER BY \u5b50\u53e5\u53ea\u5728\u4e24\u79cd\u4e25\u683c\u7684\u6761\u4ef6\u4e0b\u4f7f\u7528\u7d22\u5f15\u3002<\/p>\n
orDER BY\u4e2d\u6240\u6709\u7684\u5217\u5fc5\u987b\u5305\u542b\u5728\u76f8\u540c\u7684\u7d22\u5f15\u4e2d\u5e76\u4fdd\u6301\u5728\u7d22\u5f15\u4e2d\u7684\u6392\u5217\u987a\u5e8f\u3002<\/p>\n
orDER BY\u4e2d\u6240\u6709\u7684\u5217\u5fc5\u987b\u5b9a\u4e49\u4e3a\u975e\u7a7a\u3002<\/p>\n
Where\u5b50\u53e5\u4f7f\u7528\u7684\u7d22\u5f15\u548cORDER BY\u5b50\u53e5\u4e2d\u6240\u4f7f\u7528\u7684\u7d22\u5f15\u4e0d\u80fd\u5e76\u5217\u3002<\/p>\n
\u4f8b\u5982: \u8868DEPT\u5305\u542b\u4ee5\u4e0b\u5217:<\/p>\n
DEPT_CODE PK NOT NULL<\/p>\n
DEPT_DESC NOT NULL<\/p>\n
DEPT_TYPE NULL<\/p>\n
\u4f4e\u6548: (\u7d22\u5f15\u4e0d\u88ab\u4f7f\u7528)<\/p>\n
Select DEPT_CODE FROM DEPT orDER BY DEPT_TYPE<\/p>\n
\u9ad8\u6548: (\u4f7f\u7528\u7d22\u5f15)<\/p>\n
Select DEPT_CODE FROM DEPT Where DEPT_TYPE > 0<\/p>\n
\uff0830\uff09\u907f\u514d\u6539\u53d8\u7d22\u5f15\u5217\u7684\u7c7b\u578b:<\/p>\n
\u5f53\u6bd4\u8f83\u4e0d\u540c\u6570\u636e\u7c7b\u578b\u7684\u6570\u636e\u65f6\uff0c orACLE\u81ea\u52a8\u5bf9\u5217\u8fdb\u884c\u7b80\u5355\u7684\u7c7b\u578b\u8f6c\u6362\u3002 \u5047\u8bbe EMPNO\u662f\u4e00\u4e2a\u6570\u503c\u7c7b\u578b\u7684\u7d22\u5f15\u5217\uff1aSelect \u2026 FROM EMP Where EMPNO = \u2018123’\u3002 \u5b9e\u9645\u4e0a,\u7ecf\u8fc7Oracle\u7c7b\u578b\u8f6c\u6362, \u8bed\u53e5\u8f6c\u5316\u4e3a: Select \u2026 FROM EMP Where EMPNO = TO_NUMBER(\u2018123′) \u3002<\/p>\n
\u5e78\u8fd0\u7684\u662f,\u7c7b\u578b\u8f6c\u6362\u6ca1\u6709\u53d1\u751f\u5728\u7d22\u5f15\u5217\u4e0a,\u7d22\u5f15\u7684\u7528\u9014\u6ca1\u6709\u88ab\u6539\u53d8\u3002\u73b0\u5728,\u5047\u8bbeEMP_TYPE\u662f\u4e00\u4e2a\u5b57\u7b26\u7c7b\u578b\u7684\u7d22\u5f15\u5217\uff1aSelect \u2026 FROM EMP Where EMP_TYPE = 123 \u3002<\/p>\n
\u8fd9\u4e2a\u8bed\u53e5\u88abOracle\u8f6c\u6362\u4e3a: Select \u2026 FROM EMP WhereTO_NUMBER(EMP_TYPE)=123\u3002\u56e0\u4e3a\u5185\u90e8\u53d1\u751f\u7684\u7c7b\u578b\u8f6c\u6362\uff0c \u8fd9\u4e2a\u7d22\u5f15\u5c06\u4e0d\u4f1a\u88ab\u7528\u5230! \u4e3a\u4e86\u907f\u514dOracle\u5bf9\u4f60\u7684SQL\u8fdb\u884c\u9690\u5f0f\u7684\u7c7b\u578b\u8f6c\u6362\uff0c\u6700\u597d\u628a\u7c7b\u578b\u8f6c\u6362\u7528\u663e\u5f0f\u8868\u73b0\u51fa\u6765\u3002\u6ce8\u610f\u5f53\u5b57\u7b26\u548c\u6570\u503c\u6bd4\u8f83\u65f6\uff0cOracle\u4f1a\u4f18\u5148\u8f6c\u6362\u6570\u503c\u7c7b\u578b\u5230\u5b57\u7b26\u7c7b\u578b\u3002<\/p>\n
\uff0831\uff09\u9700\u8981\u5f53\u5fc3\u7684Where\u5b50\u53e5:<\/p>\n
\u67d0\u4e9bSelect \u8bed\u53e5\u4e2d\u7684Where\u5b50\u53e5\u4e0d\u4f7f\u7528\u7d22\u5f15\u3002\u8fd9\u91cc\u6709\u4e00\u4e9b\u4f8b\u5b50\uff1a<\/p>\n
(1)\u2018!=’ \u5c06\u4e0d\u4f7f\u7528\u7d22\u5f15\u3002\u8bb0\u4f4f, \u7d22\u5f15\u53ea\u80fd\u544a\u8bc9\u4f60\u4ec0\u4e48\u5b58\u5728\u4e8e\u8868\u4e2d, \u800c\u4e0d\u80fd\u544a\u8bc9\u4f60\u4ec0\u4e48\u4e0d\u5b58\u5728\u4e8e\u8868\u4e2d\u3002<\/p>\n
(2)\u2018||’\u662f\u5b57\u7b26\u8fde\u63a5\u51fd\u6570\u3002\u5c31\u8c61\u5176\u4ed6\u51fd\u6570\u90a3\u6837, \u505c\u7528\u4e86\u7d22\u5f15\u3002<\/p>\n
(3)\u2018+’\u662f\u6570\u5b66\u51fd\u6570\u3002\u5c31\u8c61\u5176\u4ed6\u6570\u5b66\u51fd\u6570\u90a3\u6837, \u505c\u7528\u4e86\u7d22\u5f15\u3002<\/p>\n
(4)\u76f8\u540c\u7684\u7d22\u5f15\u5217\u4e0d\u80fd\u4e92\u76f8\u6bd4\u8f83,\u8fd9\u5c06\u4f1a\u542f\u7528\u5168\u8868\u626b\u63cf\u3002<\/p>\n
\uff0832\uff09a. \u5982\u679c\u68c0\u7d22\u6570\u636e\u91cf\u8d85\u8fc730%\u7684\u8868\u4e2d\u8bb0\u5f55\u6570\uff0c\u4f7f\u7528\u7d22\u5f15\u5c06\u6ca1\u6709\u663e\u8457\u7684\u6548\u7387\u63d0\u9ad8\u3002<\/p>\n
b. \u5728\u7279\u5b9a\u60c5\u51b5\u4e0b\uff0c\u4f7f\u7528\u7d22\u5f15\u4e5f\u8bb8\u4f1a\u6bd4\u5168\u8868\u626b\u63cf\u6162\uff0c\u4f46\u8fd9\u662f\u540c\u4e00\u4e2a\u6570\u91cf\u7ea7\u4e0a\u7684\u533a\u522b\u3002\u800c\u901a\u5e38\u60c5\u51b5\u4e0b,\u4f7f\u7528\u7d22\u5f15\u6bd4\u5168\u8868\u626b\u63cf\u8981\u5757\u51e0\u500d\u4e43\u81f3\u51e0\u5343\u500d\uff01<\/p>\n
\uff0833\uff09\u907f\u514d\u4f7f\u7528\u8017\u8d39\u8d44\u6e90\u7684\u64cd\u4f5c\uff1a<\/p>\n
\u5e26\u6709DISTINCT,UNION,MINUS,INTERSECT,ORDER BY\u7684SQL\u8bed\u53e5\u4f1a\u542f\u52a8SQL\u5f15\u64ce\u6267\u884c\u8017\u8d39\u8d44\u6e90\u7684\u6392\u5e8f(SORT)\u529f\u80fd\u3002DISTINCT\u9700\u8981\u4e00\u6b21\u6392\u5e8f\u64cd\u4f5c\uff0c\u800c\u5176\u4ed6\u7684\u81f3\u5c11\u9700\u8981\u6267\u884c\u4e24\u6b21\u6392\u5e8f\u3002\u901a\u5e38\uff0c\u5e26\u6709UNION, MINUS , INTERSECT\u7684SQL\u8bed\u53e5\u90fd\u53ef\u4ee5\u7528\u5176\u4ed6\u65b9\u5f0f\u91cd\u5199\u3002\u5982\u679c\u4f60\u7684\u6570\u636e\u5e93\u7684SORT_AREA_SIZE\u8c03\u914d\u5f97\u597d\u3002\u4f7f\u7528UNION , MINUS, INTERSECT\u4e5f\u662f\u53ef\u4ee5\u8003\u8651\u7684, \u6bd5\u7adf\u5b83\u4eec\u7684\u53ef\u8bfb\u6027\u5f88\u5f3a\u3002<\/p>\n
\uff0834\uff09\u4f18\u5316GROUP BY\uff1a<\/p>\n
\u63d0\u9ad8GROUP BY \u8bed\u53e5\u7684\u6548\u7387\uff0c\u53ef\u4ee5\u901a\u8fc7\u5c06\u4e0d\u9700\u8981\u7684\u8bb0\u5f55\u5728GROUP BY \u4e4b\u524d\u8fc7\u6ee4\u6389\u3002\u4e0b\u9762\u4e24\u4e2a\u67e5\u8be2\u8fd4\u56de\u76f8\u540c\u7ed3\u679c\u4f46\u7b2c\u4e8c\u4e2a\u660e\u663e\u5c31\u5feb\u4e86\u8bb8\u591a\u3002<\/p>\n
\u4f4e\u6548: Select JOB , AVG(SAL) FROM EMP GROUP JOB HAVING JOB = \u2018PRESIDENT’ or JOB = \u2018MANAGER’ \u9ad8\u6548: Select JOB , AVG(SAL) FROM EMP Where JOB = \u2018PRESIDENT’ or JOB = \u2018MANAGER’ GROUP JOB<\/p>\n","protected":false},"excerpt":{"rendered":"
\u6211\u4eec\u8981\u505a\u5230\u4e0d\u4f46\u4f1a\u5199SQL\uff0c\u8fd8\u8981\u505a\u5230\u5199\u51fa\u6027\u80fd\u4f18\u826f\u7684SQL\u8bed\u53e5\u3002 \uff081\uff09...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-442","post","type-post","status-publish","format-standard","hentry","category-DB"],"_links":{"self":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts\/442","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=442"}],"version-history":[{"count":0,"href":"https:\/\/www.poloo.org\/index.php?rest_route=\/wp\/v2\/posts\/442\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=442"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=442"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.poloo.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=442"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}