{"id":195767,"date":"2024-11-13T17:44:19","date_gmt":"2024-11-13T09:44:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/195767\/"},"modified":"2024-11-13T17:44:20","modified_gmt":"2024-11-13T09:44:20","slug":"%e5%9c%a8oracle%e5%84%aa%e5%8c%96%e4%b8%ad%e6%89%80%e7%94%a8%e5%88%b0%e7%9a%84%e8%aa%9e%e5%8f%a5%e6%9c%89%e5%93%aa%e4%ba%9b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/195767\/","title":{"rendered":"\u5728Oracle\u512a\u5316\u4e2d\u6240\u7528\u5230\u7684\u8a9e\u53e5\u6709\u54ea\u4e9b"},"content":{"rendered":"

\u5728Oracle\u512a\u5316\u4e2d\u6240\u7528\u5230\u7684\u8a9e\u53e5\u6709\u54ea\u4e9b<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0cOracle\u6578\u64da\u5eab\u56e0\u5176\u5f37\u5927\u7684\u529f\u80fd\u548c\u9748\u6d3b\u6027\u800c\u53d7\u5230\u5ee3\u6cdb\u4f7f\u7528\u3002\u70ba\u4e86\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u512a\u5316\u67e5\u8a62\u8a9e\u53e5\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5728Oracle\u512a\u5316\u4e2d\u5e38\u7528\u7684\u8a9e\u53e5\u53ca\u5176\u61c9\u7528\u3002<\/p>\n

1. \u4f7f\u7528EXPLAIN PLAN<\/h2>\n

\u5728\u9032\u884c\u67e5\u8a62\u512a\u5316\u4e4b\u524d\uff0c\u4e86\u89e3\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002Oracle\u63d0\u4f9b\u4e86EXPLAIN PLAN\u8a9e\u53e5\uff0c\u5e6b\u52a9\u7528\u6236\u67e5\u770b\u67e5\u8a62\u7684\u57f7\u884c\u8def\u5f91\u3002<\/p>\n

EXPLAIN PLAN FOR\nSELECT * FROM employees WHERE department_id = 10;<\/code><\/pre>\n
\u57f7\u884c\u4e0a\u8ff0\u8a9e\u53e5\u5f8c\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\u4f86\u67e5\u770b\u57f7\u884c\u8a08\u5283\uff1a<\/p>\n
SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);<\/code><\/pre>\n
2. \u4f7f\u7528\u7d22\u5f15<\/h2>\n
\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u7684\u95dc\u9375\u3002\u901a\u904e\u5275\u5efa\u9069\u7576\u7684\u7d22\u5f15\uff0c\u53ef\u4ee5\u986f\u8457\u6e1b\u5c11\u67e5\u8a62\u7684\u57f7\u884c\u6642\u9593\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u7d22\u5f15\u7684\u8a9e\u53e5\uff1a<\/p>\n
CREATE INDEX idx_department ON employees(department_id);<\/code><\/pre>\n
\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u7d22\u5f15\u53ef\u4ee5\u52a0\u5feb\u6578\u64da\u6aa2\u7d22\u901f\u5ea6\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\u3002<\/p>\n
3. \u4f7f\u7528\u805a\u5408\u51fd\u6578<\/h2>\n
\u5728\u9032\u884c\u6578\u64da\u5206\u6790\u6642\uff0c\u805a\u5408\u51fd\u6578\uff08\u5982SUM\u3001AVG\u3001COUNT\u7b49\uff09\u53ef\u4ee5\u5e6b\u52a9\u5feb\u901f\u8a08\u7b97\u6578\u64da\u7684\u7d71\u8a08\u4fe1\u606f\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528\u805a\u5408\u51fd\u6578\u7684\u793a\u4f8b\uff1a<\/p>\n
SELECT department_id, COUNT(*) AS employee_count\nFROM employees\nGROUP BY department_id;<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u53ef\u4ee5\u5feb\u901f\u7372\u5f97\u6bcf\u500b\u90e8\u9580\u7684\u54e1\u5de5\u6578\u91cf\uff0c\u4e26\u4e14\u901a\u5e38\u6bd4\u9010\u884c\u8a08\u7b97\u66f4\u9ad8\u6548\u3002<\/p>\n
4. \u4f7f\u7528JOIN\u512a\u5316<\/h2>\n
\u5728\u591a\u8868\u67e5\u8a62\u4e2d\uff0cJOIN\u64cd\u4f5c\u7684\u6548\u7387\u5c0d\u6574\u9ad4\u67e5\u8a62\u6027\u80fd\u5f71\u97ff\u5f88\u5927\u3002\u4f7f\u7528INNER JOIN\u3001LEFT JOIN\u7b49\u6642\uff0c\u61c9\u6839\u64da\u5be6\u969b\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684JOIN\u985e\u578b\u3002<\/p>\n
SELECT e.first_name, e.last_name, d.department_name\nFROM employees e\nJOIN departments d ON e.department_id = d.department_id;<\/code><\/pre>\n
\u6b64\u5916\uff0c\u78ba\u4fdd\u5728JOIN\u7684\u5b57\u6bb5\u4e0a\u6709\u7d22\u5f15\uff0c\u53ef\u4ee5\u9032\u4e00\u6b65\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n
5. \u4f7f\u7528WHERE\u5b50\u53e5\u904e\u6ffe\u6578\u64da<\/h2>\n
\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528WHERE\u5b50\u53e5\u53ef\u4ee5\u6709\u6548\u5730\u904e\u6ffe\u4e0d\u5fc5\u8981\u7684\u6578\u64da\uff0c\u5f9e\u800c\u6e1b\u5c11\u67e5\u8a62\u7684\u8ca0\u64d4\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528WHERE\u5b50\u53e5\u7684\u793a\u4f8b\uff1a<\/p>\n
SELECT * FROM employees\nWHERE hire_date > '2020-01-01';<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u50c5\u8fd4\u56de2020\u5e74\u4ee5\u5f8c\u96c7\u7528\u7684\u54e1\u5de5\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n
6. \u4f7f\u7528LIMIT\u548cROWNUM<\/h2>\n
\u5728\u9700\u8981\u9650\u5236\u8fd4\u56de\u7d50\u679c\u6578\u91cf\u7684\u60c5\u6cc1\u4e0b\uff0c\u53ef\u4ee5\u4f7f\u7528LIMIT\u6216ROWNUM\u4f86\u63a7\u5236\u67e5\u8a62\u7d50\u679c\u7684\u5927\u5c0f\u3002\u9019\u5c0d\u65bc\u63d0\u9ad8\u6027\u80fd\u5c24\u5176\u91cd\u8981\u3002<\/p>\n
SELECT * FROM employees\nWHERE ROWNUM <= 10;<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u50c5\u8fd4\u56de\u524d10\u689d\u8a18\u9304\uff0c\u6e1b\u5c11\u4e86\u6578\u64da\u7684\u50b3\u8f38\u91cf\u3002<\/p>\n
7. \u4f7f\u7528PL\/SQL\u9032\u884c\u6279\u91cf\u8655\u7406<\/h2>\n
\u5728\u9700\u8981\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0c\u4f7f\u7528PL\/SQL\u9032\u884c\u6279\u91cf\u64cd\u4f5c\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u6027\u80fd\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684PL\/SQL\u793a\u4f8b\uff1a<\/p>\n
BEGIN\n  FOR rec IN (SELECT * FROM employees) LOOP\n    -- \u57f7\u884c\u67d0\u4e9b\u64cd\u4f5c\n  END LOOP;\nEND;<\/code><\/pre>\n
\u9019\u6a23\u7684\u6279\u91cf\u8655\u7406\u53ef\u4ee5\u6e1b\u5c11\u4e0a\u4e0b\u6587\u5207\u63db\u7684\u958b\u92b7\uff0c\u5f9e\u800c\u63d0\u9ad8\u6027\u80fd\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5728Oracle\u6578\u64da\u5eab\u7684\u512a\u5316\u904e\u7a0b\u4e2d\uff0c\u4f7f\u7528\u6b63\u78ba\u7684\u8a9e\u53e5\u548c\u6280\u8853\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u901a\u904e\u4f7f\u7528EXPLAIN PLAN\u3001\u7d22\u5f15\u3001\u805a\u5408\u51fd\u6578\u3001JOIN\u512a\u5316\u3001WHERE\u5b50\u53e5\u3001LIMIT\u548cROWNUM\u4ee5\u53caPL\/SQL\u9032\u884c\u6279\u91cf\u8655\u7406\uff0c\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002\u9019\u4e9b\u6280\u8853\u4e0d\u50c5\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u512a\u5316\u6578\u64da\u5eab\u67e5\u8a62\uff0c\u9084\u80fd\u63d0\u5347\u6574\u9ad4\u7cfb\u7d71\u7684\u6548\u7387\u3002<\/p>\n
\u5982\u679c\u60a8\u5c0d\u65bc\u5982\u4f55\u5728\u60a8\u7684\u696d\u52d9\u4e2d\u5be6\u65bd\u9019\u4e9b\u512a\u5316\u6280\u8853\u6709\u8208\u8da3\uff0c\u6216\u8005\u60f3\u4e86\u89e3\u66f4\u591a\u95dc\u65bc\u9999\u6e2fVPS<\/a>\u548c\u96f2\u4f3a\u670d\u5668<\/a>\u7684\u8cc7\u8a0a\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8a73\u7d30\u8cc7\u6599\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22Oracle\u512a\u5316\u4e2d\u5e38\u7528\u7684\u8a9e\u53e5\uff0c\u5305\u62ec\u7d22\u5f15\u3001\u67e5\u8a62\u91cd\u5beb\u548c\u57f7\u884c\u8a08\u5283\u5206\u6790\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u7684\u95dc\u9375\u6280\u5de7\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-195767","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/195767","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=195767"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/195767\/revisions"}],"predecessor-version":[{"id":195768,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/195767\/revisions\/195768"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=195767"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=195767"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=195767"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}