{"id":60429,"date":"2024-10-13T02:47:16","date_gmt":"2024-10-12T18:47:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/60429\/"},"modified":"2024-10-13T02:47:17","modified_gmt":"2024-10-12T18:47:17","slug":"db2%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b8%e5%92%8coracle%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%8d%e5%90%8c%e4%b9%8b%e8%99%95%e6%9c%89%e5%93%aa%e4%ba%9b%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/60429\/","title":{"rendered":"DB2\u5e38\u7528\u51fd\u6578\u548cOracle\u6578\u64da\u5eab\u4e0d\u540c\u4e4b\u8655\u6709\u54ea\u4e9b\uff1f"},"content":{"rendered":"<h1 id=\"db2%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b8%e5%92%8coracle%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%8d%e5%90%8c%e4%b9%8b%e8%99%95%e6%9c%89%e5%93%aa%e4%ba%9b%ef%bc%9f-MhyTOhRVlL\">DB2\u5e38\u7528\u51fd\u6578\u548cOracle\u6578\u64da\u5eab\u4e0d\u540c\u4e4b\u8655\u6709\u54ea\u4e9b\uff1f<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cIBM\u7684DB2\u548cOracle\u6578\u64da\u5eab\u90fd\u662f\u975e\u5e38\u53d7\u6b61\u8fce\u7684\u9078\u64c7\u3002\u96d6\u7136\u5b83\u5011\u90fd\u63d0\u4f9b\u4e86\u5f37\u5927\u7684\u6578\u64da\u8655\u7406\u80fd\u529b\uff0c\u4f46\u5728\u51fd\u6578\u7684\u4f7f\u7528\u548c\u8a9e\u6cd5\u4e0a\u537b\u5b58\u5728\u4e00\u4e9b\u986f\u8457\u7684\u5dee\u7570\u3002\u672c\u6587\u5c07\u63a2\u8a0eDB2\u5e38\u7528\u51fd\u6578\u8207Oracle\u6578\u64da\u5eab\u4e4b\u9593\u7684\u4e0d\u540c\u4e4b\u8655\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u597d\u5730\u7406\u89e3\u9019\u5169\u7a2e\u6578\u64da\u5eab\u7684\u7279\u6027\u3002<\/p>\n<h2 id=\"1-%e5%ad%97%e7%ac%a6%e4%b8%b2%e8%99%95%e7%90%86%e5%87%bd%e6%95%b8-MhyTOhRVlL\">1. \u5b57\u7b26\u4e32\u8655\u7406\u51fd\u6578<\/h2>\n<p>\u5728\u5b57\u7b26\u4e32\u8655\u7406\u65b9\u9762\uff0cDB2\u548cOracle\u90fd\u63d0\u4f9b\u4e86\u591a\u7a2e\u51fd\u6578\uff0c\u4f46\u5176\u8a9e\u6cd5\u548c\u529f\u80fd\u7565\u6709\u4e0d\u540c\u3002<\/p>\n<ul>\n<li><strong>\u9023\u63a5\u5b57\u7b26\u4e32\uff1a<\/strong>\u5728DB2\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528<code>CONCAT<\/code>\u51fd\u6578\u4f86\u9023\u63a5\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a<\/li>\n<pre><code>SELECT CONCAT('Hello', ' World') FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<li>\u800c\u5728Oracle\u4e2d\uff0c\u5247\u53ef\u4ee5\u4f7f\u7528<code>||<\/code>\u904b\u7b97\u7b26\u4f86\u9054\u6210\u76f8\u540c\u7684\u6548\u679c\uff1a<\/li>\n<pre><code>SELECT 'Hello' || ' World' FROM dual;<\/code><\/pre>\n<\/ul>\n<h2 id=\"2-%e6%97%a5%e6%9c%9f%e5%92%8c%e6%99%82%e9%96%93%e5%87%bd%e6%95%b8-MhyTOhRVlL\">2. \u65e5\u671f\u548c\u6642\u9593\u51fd\u6578<\/h2>\n<p>\u65e5\u671f\u548c\u6642\u9593\u7684\u8655\u7406\u5728DB2\u548cOracle\u4e2d\u4e5f\u6709\u4e0d\u540c\u7684\u5be6\u73fe\u65b9\u5f0f\u3002<\/p>\n<ul>\n<li><strong>\u7372\u53d6\u7576\u524d\u65e5\u671f\uff1a<\/strong>\u5728DB2\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528<code>CURRENT DATE<\/code>\u4f86\u7372\u53d6\u7576\u524d\u65e5\u671f\uff1a<\/li>\n<pre><code>SELECT CURRENT DATE FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<li>\u800c\u5728Oracle\u4e2d\uff0c\u5247\u4f7f\u7528<code>SYSDATE<\/code>\uff1a<\/li>\n<pre><code>SELECT SYSDATE FROM dual;<\/code><\/pre>\n<\/ul>\n<h2 id=\"3-%e6%95%b8%e5%ad%b8%e5%87%bd%e6%95%b8-MhyTOhRVlL\">3. \u6578\u5b78\u51fd\u6578<\/h2>\n<p>\u6578\u5b78\u51fd\u6578\u5728\u5169\u8005\u4e4b\u9593\u7684\u5dee\u7570\u4e5f\u503c\u5f97\u6ce8\u610f\u3002<\/p>\n<ul>\n<li><strong>\u53d6\u6574\u51fd\u6578\uff1a<\/strong>\u5728DB2\u4e2d\uff0c\u4f7f\u7528<code>ROUND<\/code>\u51fd\u6578\u4f86\u53d6\u6574\uff1a<\/li>\n<pre><code>SELECT ROUND(123.456) FROM SYSIBM.SYSDUMMY1;<\/code><\/pre>\n<li>\u800c\u5728Oracle\u4e2d\uff0c\u5247\u540c\u6a23\u4f7f\u7528<code>ROUND<\/code>\u51fd\u6578\uff0c\u4f46\u5176\u7528\u6cd5\u53ef\u80fd\u6703\u6709\u6240\u4e0d\u540c\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5c0f\u6578\u4f4d\u6578\u6642\uff1a<\/li>\n<pre><code>SELECT ROUND(123.456, 1) FROM dual;<\/code><\/pre>\n<\/ul>\n<h2 id=\"4-%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8-MhyTOhRVlL\">4. \u805a\u5408\u51fd\u6578<\/h2>\n<p>\u805a\u5408\u51fd\u6578\u5728DB2\u548cOracle\u4e2d\u4e5f\u6709\u76f8\u4f3c\u4e4b\u8655\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528\u7684\u65b9\u5f0f\u548c\u8fd4\u56de\u7684\u7d50\u679c\u53ef\u80fd\u6703\u6709\u6240\u4e0d\u540c\u3002<\/p>\n<ul>\n<li><strong>\u8a08\u6578\u51fd\u6578\uff1a<\/strong>\u5728DB2\u4e2d\uff0c\u4f7f\u7528<code>COUNT<\/code>\u51fd\u6578\u4f86\u8a08\u7b97\u884c\u6578\uff1a<\/li>\n<pre><code>SELECT COUNT(*) FROM employees;<\/code><\/pre>\n<li>\u5728Oracle\u4e2d\uff0c\u4f7f\u7528\u65b9\u5f0f\u76f8\u540c\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0cOracle\u9084\u652f\u6301<code>COUNT(DISTINCT column_name)<\/code>\u4f86\u8a08\u7b97\u4e0d\u540c\u503c\u7684\u6578\u91cf\uff1a<\/li>\n<pre><code>SELECT COUNT(DISTINCT department_id) FROM employees;<\/code><\/pre>\n<\/ul>\n<h2 id=\"5-%e5%85%b6%e4%bb%96%e5%87%bd%e6%95%b8%e7%9a%84%e5%b7%ae%e7%95%b0-MhyTOhRVlL\">5. \u5176\u4ed6\u51fd\u6578\u7684\u5dee\u7570<\/h2>\n<p>\u9664\u4e86\u4e0a\u8ff0\u51fd\u6578\u5916\uff0cDB2\u548cOracle\u5728\u5176\u4ed6\u4e00\u4e9b\u51fd\u6578\u7684\u5be6\u73fe\u4e0a\u4e5f\u5b58\u5728\u5dee\u7570\u3002\u4f8b\u5982\uff0cDB2\u7684<code>COALESCE<\/code>\u51fd\u6578\u548cOracle\u7684<code>NVL<\/code>\u51fd\u6578\u90fd\u53ef\u4ee5\u7528\u4f86\u8655\u7406\u7a7a\u503c\uff0c\u4f46\u5176\u8a9e\u6cd5\u548c\u4f7f\u7528\u60c5\u5883\u6709\u6240\u4e0d\u540c\u3002<\/p>\n<ul>\n<li><strong>DB2\u7684COALESCE\uff1a<\/strong><\/li>\n<pre><code>SELECT COALESCE(column_name, 'default_value') FROM table_name;<\/code><\/pre>\n<li><strong>Oracle\u7684NVL\uff1a<\/strong><\/li>\n<pre><code>SELECT NVL(column_name, 'default_value') FROM table_name;<\/code><\/pre>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-MhyTOhRVlL\">\u7e3d\u7d50<\/h2>\n<p>\u7e3d\u7684\u4f86\u8aaa\uff0cDB2\u548cOracle\u6578\u64da\u5eab\u5728\u51fd\u6578\u7684\u4f7f\u7528\u4e0a\u5b58\u5728\u591a\u65b9\u9762\u7684\u5dee\u7570\uff0c\u9019\u4e9b\u5dee\u7570\u53ef\u80fd\u6703\u5f71\u97ff\u5230\u958b\u767c\u8005\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u7684\u9078\u64c7\u548c\u4f7f\u7528\u3002\u4e86\u89e3\u9019\u4e9b\u4e0d\u540c\u4e4b\u8655\u4e0d\u50c5\u6709\u52a9\u65bc\u63d0\u9ad8\u958b\u767c\u6548\u7387\uff0c\u9084\u80fd\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u597d\u5730\u9069\u61c9\u4e0d\u540c\u7684\u6578\u64da\u5eab\u74b0\u5883\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u7121\u8ad6\u662f\u4f7f\u7528DB2\u9084\u662fOracle\uff0c\u9078\u64c7\u5408\u9069\u7684<em><a href=\"https:\/\/server.hk\">VPS<\/a><\/em>\u6216<em><a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a><\/em>\u90fd\u80fd\u70ba\u60a8\u7684\u696d\u52d9\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002\u4e86\u89e3\u66f4\u591a\u4fe1\u606f\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22DB2\u5e38\u7528\u51fd\u6578\u8207Oracle\u6578\u64da\u5eab\u4e4b\u9593\u7684\u4e3b\u8981\u5dee\u7570\uff0c\u4e86\u89e3\u5404\u81ea\u7684\u7279\u9ede\u548c\u61c9\u7528\u5834\u666f\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-60429","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60429","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=60429"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60429\/revisions"}],"predecessor-version":[{"id":60430,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60429\/revisions\/60430"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=60429"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=60429"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=60429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}