{"id":96218,"date":"2024-10-20T07:35:18","date_gmt":"2024-10-19T23:35:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/96218\/"},"modified":"2024-10-20T07:35:18","modified_gmt":"2024-10-19T23:35:18","slug":"oracle%e5%84%aa%e5%8c%96%e6%9f%a5%e8%a9%a2%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%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/96218\/","title":{"rendered":"Oracle\u512a\u5316\u67e5\u8a62\u4e2d\u6240\u7528\u5230\u7684\u8a9e\u53e5\u6709\u54ea\u4e9b\uff1f"},"content":{"rendered":"<h1 id=\"oracle%e5%84%aa%e5%8c%96%e6%9f%a5%e8%a9%a2%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%ef%bc%9f-YsmOBnaUKf\">Oracle\u512a\u5316\u67e5\u8a62\u4e2d\u6240\u7528\u5230\u7684\u8a9e\u53e5\u6709\u54ea\u4e9b\uff1f<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u67e5\u8a62\u512a\u5316\u662f\u63d0\u5347\u6027\u80fd\u7684\u95dc\u9375\u56e0\u7d20\u4e4b\u4e00\u3002Oracle\u6578\u64da\u5eab\u63d0\u4f9b\u4e86\u591a\u7a2e\u8a9e\u53e5\u548c\u5de5\u5177\u4f86\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u512a\u5316\u67e5\u8a62\u6027\u80fd\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5728Oracle\u4e2d\u5e38\u7528\u7684\u67e5\u8a62\u512a\u5316\u8a9e\u53e5\u53ca\u5176\u61c9\u7528\u3002<\/p>\n<h2 id=\"1-%e4%bd%bf%e7%94%a8explain-plan-YsmOBnaUKf\">1. \u4f7f\u7528EXPLAIN PLAN<\/h2>\n<p>EXPLAIN PLAN\u8a9e\u53e5\u7528\u65bc\u986f\u793aOracle\u5982\u4f55\u57f7\u884cSQL\u67e5\u8a62\u3002\u901a\u904e\u5206\u6790\u57f7\u884c\u8a08\u5283\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u4e86\u89e3\u67e5\u8a62\u7684\u6027\u80fd\u74f6\u9838\uff0c\u4e26\u91dd\u5c0d\u6027\u5730\u9032\u884c\u512a\u5316\u3002<\/p>\n<pre><code>EXPLAIN PLAN FOR\nSELECT * FROM employees WHERE department_id = 10;<\/code><\/pre>\n<p>\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<pre><code>SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);<\/code><\/pre>\n<h2 id=\"2-%e4%bd%bf%e7%94%a8index-YsmOBnaUKf\">2. \u4f7f\u7528INDEX<\/h2>\n<p>\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u7684\u91cd\u8981\u5de5\u5177\u3002\u901a\u904e\u5728\u8868\u7684\u67d0\u4e9b\u5217\u4e0a\u5275\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u52a0\u901f\u67e5\u8a62\u7684\u57f7\u884c\u901f\u5ea6\u3002\u4ee5\u4e0b\u662f\u5275\u5efa\u7d22\u5f15\u7684\u8a9e\u53e5\uff1a<\/p>\n<pre><code>CREATE INDEX idx_department ON employees(department_id);<\/code><\/pre>\n<p>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u7d22\u5f15\u53ef\u4ee5\u986f\u8457\u6e1b\u5c11\u6578\u64da\u6383\u63cf\u7684\u884c\u6578\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8join%e5%84%aa%e5%8c%96-YsmOBnaUKf\">3. \u4f7f\u7528JOIN\u512a\u5316<\/h2>\n<p>\u5728\u591a\u8868\u67e5\u8a62\u4e2d\uff0cJOIN\u64cd\u4f5c\u7684\u6027\u80fd\u5c0d\u6574\u9ad4\u67e5\u8a62\u901f\u5ea6\u5f71\u97ff\u5f88\u5927\u3002\u4f7f\u7528\u5408\u9069\u7684JOIN\u985e\u578b\uff08\u5982INNER JOIN\u3001LEFT JOIN\u7b49\uff09\u548c\u689d\u4ef6\u53ef\u4ee5\u512a\u5316\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<pre><code>SELECT e.first_name, e.last_name, d.department_name\nFROM employees e\nJOIN departments d ON e.department_id = d.department_id\nWHERE d.location_id = 1000;<\/code><\/pre>\n<h2 id=\"4-%e4%bd%bf%e7%94%a8where%e5%ad%90%e5%8f%a5%e9%81%8e%e6%bf%be%e6%95%b8%e6%93%9a-YsmOBnaUKf\">4. \u4f7f\u7528WHERE\u5b50\u53e5\u904e\u6ffe\u6578\u64da<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528WHERE\u5b50\u53e5\u53ef\u4ee5\u6709\u6548\u5730\u904e\u6ffe\u4e0d\u5fc5\u8981\u7684\u6578\u64da\uff0c\u6e1b\u5c11\u67e5\u8a62\u7684\u8fd4\u56de\u7d50\u679c\u96c6\u5927\u5c0f\uff0c\u5f9e\u800c\u63d0\u9ad8\u6027\u80fd\u3002<\/p>\n<pre><code>SELECT * FROM employees\nWHERE hire_date &gt; '2020-01-01';<\/code><\/pre>\n<h2 id=\"5-%e4%bd%bf%e7%94%a8group-by%e5%92%8chaving-YsmOBnaUKf\">5. \u4f7f\u7528GROUP BY\u548cHAVING<\/h2>\n<p>\u5728\u9700\u8981\u9032\u884c\u805a\u5408\u8a08\u7b97\u7684\u67e5\u8a62\u4e2d\uff0c\u4f7f\u7528GROUP BY\u548cHAVING\u5b50\u53e5\u53ef\u4ee5\u6709\u6548\u5730\u7d44\u7e54\u6578\u64da\u4e26\u9032\u884c\u8a08\u7b97\u3002\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u6578\u64da\u7684\u8655\u7406\u91cf\u3002<\/p>\n<pre><code>SELECT department_id, COUNT(*) AS employee_count\nFROM employees\nGROUP BY department_id\nHAVING COUNT(*) &gt; 5;<\/code><\/pre>\n<h2 id=\"6-%e4%bd%bf%e7%94%a8limit%e5%92%8crownum-YsmOBnaUKf\">6. \u4f7f\u7528LIMIT\u548cROWNUM<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528LIMIT\u6216ROWNUM\u53ef\u4ee5\u9650\u5236\u8fd4\u56de\u7684\u884c\u6578\uff0c\u9019\u5c0d\u65bc\u9700\u8981\u5feb\u901f\u67e5\u770b\u90e8\u5206\u6578\u64da\u7684\u60c5\u6cc1\u7279\u5225\u6709\u7528\u3002<\/p>\n<pre><code>SELECT * FROM employees\nWHERE ROWNUM &lt;= 10;<\/code><\/pre>\n<h2 id=\"7-%e4%bd%bf%e7%94%a8%e5%88%86%e6%9e%90%e5%87%bd%e6%95%b8-YsmOBnaUKf\">7. \u4f7f\u7528\u5206\u6790\u51fd\u6578<\/h2>\n<p>Oracle\u63d0\u4f9b\u4e86\u591a\u7a2e\u5206\u6790\u51fd\u6578\uff0c\u5982ROW_NUMBER()\u3001RANK()\u7b49\uff0c\u9019\u4e9b\u51fd\u6578\u53ef\u4ee5\u5728\u4e0d\u9700\u8981\u984d\u5916GROUP BY\u7684\u60c5\u6cc1\u4e0b\u9032\u884c\u6578\u64da\u5206\u6790\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<pre><code>SELECT employee_id, first_name, last_name,\n       ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY hire_date) AS rn\nFROM employees;<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-YsmOBnaUKf\">\u7e3d\u7d50<\/h2>\n<p>\u5728Oracle\u6578\u64da\u5eab\u4e2d\uff0c\u512a\u5316\u67e5\u8a62\u6027\u80fd\u662f\u63d0\u5347\u61c9\u7528\u7a0b\u5e8f\u6548\u7387\u7684\u95dc\u9375\u3002\u901a\u904e\u4f7f\u7528EXPLAIN PLAN\u3001\u7d22\u5f15\u3001JOIN\u512a\u5316\u3001WHERE\u5b50\u53e5\u3001GROUP BY\u3001LIMIT\u3001\u4ee5\u53ca\u5206\u6790\u51fd\u6578\u7b49\u8a9e\u53e5\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u63d0\u9ad8\u67e5\u8a62\u7684\u57f7\u884c\u901f\u5ea6\u548c\u6548\u7387\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6027\u80fd\u7684\u61c9\u7528\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u5982<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u6216<a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a>\uff0c\u4e5f\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3Oracle\u512a\u5316\u67e5\u8a62\u4e2d\u5e38\u7528\u7684\u8a9e\u53e5\uff0c\u5305\u62ecEXPLAIN PLAN\u3001INDEX\u3001JOIN\u7b49\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\u8207\u6027\u80fd\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-96218","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96218","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=96218"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96218\/revisions"}],"predecessor-version":[{"id":96219,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/96218\/revisions\/96219"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=96218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=96218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=96218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}